A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a malicious user to elevate their privileges within the guest.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option     may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a     modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a     malicious user to elevate their privileges within the guest. (CVE-2021-20263)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote CentOS Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the qemu-kvm-6.1.0-3.el9 build changelog.

  - use-after-free during packet reassembly [rhel-av-8]) (CVE-2019-15890)

  - A flaw was found in QEMU in the implementation of the Pointer Authentication (PAuth) support for ARM     introduced in version 4.0 and fixed in version 5.0.0. A general failure of the signature generation     process caused every PAuth-enforced pointer to be signed with the same signature. A local attacker could     obtain the signature of a protected pointer and abuse this flaw to bypass PAuth protection for all     programs running on QEMU. (CVE-2020-10702)

  - A potential DoS flaw was found in the virtio-fs shared file system daemon (virtiofsd) implementation of     the QEMU version >= v5.0. Virtio-fs is meant to share a host file system directory with a guest via     virtio-fs device. If the guest opens the maximum number of file descriptors under the shared directory, a     denial of service may occur. This flaw allows a guest user/process to cause this denial of service on the     host. (CVE-2020-10717)

  - An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator.
    This flaw occurs in the icmp6_send_echoreply() routine while replying to an ICMP echo request, also known     as ping. This flaw allows a malicious guest to leak the contents of the host memory, resulting in possible     information disclosure. This flaw affects versions of libslirp before 4.3.1. (CVE-2020-10756)

  - An assertion failure issue was found in the Network Block Device(NBD) Server in all QEMU versions before     QEMU 5.0.1. This flaw occurs when an nbd-client sends a spec-compliant request that is near the boundary     of maximum permitted request length. A remote nbd-client could use this flaw to crash the qemu-nbd server     resulting in a denial of service. (CVE-2020-10761)

  - out-of-bounds r/w access issue while processing usb packets [rhel-av-8.3.0]) (CVE-2020-14364)

  - OOB heap access via an unexpected response of iSCSI Server [rhel-av-8.2.0]) (CVE-2020-1711)

  - A use after free vulnerability in ip_reass() in ip_input.c of libslirp 4.2.0 and prior releases allows     crafted packets to cause a denial of service. (CVE-2020-1983)

  - A flaw was found in the memory management API of QEMU during the initialization of a memory region cache.
    This issue could lead to an out-of-bounds write access to the MSI-X table while performing MMIO     operations. A guest user may abuse this flaw to crash the QEMU process on the host, resulting in a denial     of service. This flaw affects QEMU versions prior to 5.2.0. (CVE-2020-27821)

  - A flaw was found in qemu. A host privilege escalation issue was found in the virtio-fs shared file system     daemon where a privileged guest user is able to create a device special file in the shared directory and     use it to r/w access host devices. (CVE-2020-35517)

  - OOB buffer access while emulating tcp protocols in tcp_emu() [rhel-av-8.2.0]) (CVE-2020-7039)

  - potential OOB access due to unsafe snprintf() usages [rhel-av-8.2.0]) (CVE-2020-8608)

  - An out-of-bounds heap buffer access issue was found in the ARM Generic Interrupt Controller emulator of     QEMU up to and including qemu 4.2.0on aarch64 platform. The issue occurs because while writing an     interrupt ID to the controller memory area, it is not masked to be 4 bits wide. It may lead to the said     issue while updating controller state fields and their subsequent processing. A privileged guest user may     use this flaw to crash the QEMU process on the host resulting in DoS scenario. (CVE-2021-20221)

  - A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option     may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a     modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a     malicious user to elevate their privileges within the guest. (CVE-2021-20263)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote host is affected by the vulnerability described in GLSA-202208-27 (QEMU: Multiple Vulnerabilities)

  - QEMU 4.2.0 has a use-after-free in hw/net/e1000e_core.c because a guest OS user can trigger an e1000e     packet with the data's address set to the e1000e's MMIO address. (CVE-2020-15859)

  - hw/net/xgmac.c in the XGMAC Ethernet controller in QEMU before 07-20-2020 has a buffer overflow. This     occurs during packet transmission and affects the highbank and midway emulated machines. A guest user or     process could use this flaw to crash the QEMU process on the host, resulting in a denial of service or     potential privileged code execution. This was fixed in commit 5519724a13664b43e225ca05351c60b4468e4555.
    (CVE-2020-15863)

  - In QEMU through 5.0.0, an assertion failure can occur in the network packet processing. This issue affects     the e1000e and vmxnet3 network devices. A malicious guest user/process could use this flaw to abort the     QEMU process on the host, resulting in a denial of service condition in net_tx_pkt_add_raw_fragment in     hw/net/net_tx_pkt.c. (CVE-2020-16092)

  - A NULL pointer dereference flaw was found in the SCSI emulation support of QEMU in versions before 6.0.0.
    This flaw allows a privileged guest user to crash the QEMU process on the host, resulting in a denial of     service. The highest threat from this vulnerability is to system availability. (CVE-2020-35504)

  - A NULL pointer dereference flaw was found in the am53c974 SCSI host bus adapter emulation of QEMU in     versions before 6.0.0. This issue occurs while handling the 'Information Transfer' command. This flaw     allows a privileged guest user to crash the QEMU process on the host, resulting in a denial of service.
    The highest threat from this vulnerability is to system availability. (CVE-2020-35505)

  - A use-after-free vulnerability was found in the am53c974 SCSI host bus adapter emulation of QEMU in     versions before 6.0.0 during the handling of the 'Information Transfer' command (CMD_TI). This flaw allows     a privileged guest user to crash the QEMU process on the host, resulting in a denial of service or     potential code execution with the privileges of the QEMU process. (CVE-2020-35506)

  - A flaw was found in qemu. A host privilege escalation issue was found in the virtio-fs shared file system     daemon where a privileged guest user is able to create a device special file in the shared directory and     use it to r/w access host devices. (CVE-2020-35517)

  - An integer overflow issue was found in the vmxnet3 NIC emulator of the QEMU for versions up to v5.2.0. It     may occur if a guest was to supply invalid values for rx/tx queue size or other NIC parameters. A     privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.
    (CVE-2021-20203)

  - An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing     transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid     values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The     highest threat from this vulnerability is to system availability. (CVE-2021-20257)

  - A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option     may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a     modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a     malicious user to elevate their privileges within the guest. (CVE-2021-20263)

  - The patch for CVE-2020-17380/CVE-2020-25085 was found to be ineffective, thus making QEMU vulnerable to     the out-of-bounds read/write access issues previously found in the SDHCI controller emulation code. This     flaw allows a malicious privileged guest to crash the QEMU process on the host, resulting in a denial of     service or potential code execution. QEMU up to (including) 5.2.0 is affected by this. (CVE-2021-3409)

  - A potential stack overflow via infinite loop issue was found in various NIC emulators of QEMU in versions     up to and including 5.2.0. The issue occurs in loopback mode of a NIC wherein reentrant DMA checks get     bypassed. A guest user/process may use this flaw to consume CPU cycles or crash the QEMU process on the     host resulting in DoS scenario. (CVE-2021-3416)

  - A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a     single, large transfer request, to reduce the overhead and improve performance. The combined size of the     bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper     validation. Since the total size is not bounded, a malicious guest could use this flaw to influence the     array length and cause the QEMU process to perform an excessive allocation on the stack, resulting in a     denial of service. (CVE-2021-3527)

  - Several memory leaks were found in the virtio vhost-user GPU device (vhost-user-gpu) of QEMU in versions     up to and including 6.0. They exist in contrib/vhost-user-gpu/vhost-user-gpu.c and contrib/vhost-user-     gpu/virgl.c due to improper release of memory (i.e., free) after effective lifetime. (CVE-2021-3544)

  - An information disclosure vulnerability was found in the virtio vhost-user GPU device (vhost-user-gpu) of     QEMU in versions up to and including 6.0. The flaw exists in virgl_cmd_get_capset_info() in contrib/vhost-     user-gpu/virgl.c and could occur due to the read of uninitialized memory. A malicious guest could exploit     this issue to leak memory from the host. (CVE-2021-3545)

  - An out-of-bounds write vulnerability was found in the virtio vhost-user GPU device (vhost-user-gpu) of     QEMU in versions up to and including 6.0. The flaw occurs while processing the 'VIRTIO_GPU_CMD_GET_CAPSET'     command from the guest. It could allow a privileged guest user to crash the QEMU process on the host,     resulting in a denial of service condition, or potential code execution with the privileges of the QEMU     process. (CVE-2021-3546)

  - A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device. The issue occurs while     handling a PVRDMA_CMD_CREATE_MR command due to improper memory remapping (mremap). This flaw allows a     malicious guest to crash the QEMU process on the host. The highest threat from this vulnerability is to     system availability. (CVE-2021-3582)

  - An integer overflow was found in the QEMU implementation of VMWare's paravirtual RDMA device in versions     prior to 6.1.0. The issue occurs while handling a PVRDMA_REG_DSRHIGH write from the guest due to     improper input validation. This flaw allows a privileged guest user to make QEMU allocate a large amount     of memory, resulting in a denial of service. The highest threat from this vulnerability is to system     availability. (CVE-2021-3607)

  - A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device in versions prior to     6.1.0. The issue occurs while handling a PVRDMA_REG_DSRHIGH write from the guest and may result in a     crash of QEMU or cause undefined behavior due to the access of an uninitialized pointer. The highest     threat from this vulnerability is to system availability. (CVE-2021-3608)

  - A stack overflow vulnerability was found in the Intel HD Audio device (intel-hda) of QEMU. A malicious     guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service     condition. The highest threat from this vulnerability is to system availability. This flaw affects QEMU     versions prior to 7.0.0. (CVE-2021-3611)

  - A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs     when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. A     malicious SPICE client could use this flaw to make QEMU call free() with faked heap chunk metadata,     resulting in a crash of QEMU or potential code execution with the privileges of the QEMU process on the     host. (CVE-2021-3682)

  - An out-of-bounds write flaw was found in the UAS (USB Attached SCSI) device emulation of QEMU in versions     prior to 6.2.0-rc0. The device uses the guest supplied stream number unchecked, which can lead to out-of-     bounds access to the UASDevice->data3 and UASDevice->status3 fields. A malicious guest user could use this     flaw to crash QEMU or potentially achieve code execution with the privileges of the QEMU process on the     host. (CVE-2021-3713)

  - A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the     descriptor's address belongs to the non direct access region, due to num_buffers being set after the     virtqueue elem has been unmapped. A malicious guest could use this flaw to crash QEMU, resulting in a     denial of service condition, or potentially execute code on the host with the privileges of the QEMU     process. (CVE-2021-3748)

  - A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU. EHCI does not verify if the     Buffer Pointer overlaps with its MMIO region when it transfers the USB packets. Crafted content may be     written to the controller's registers and trigger undesirable actions (such as reset) while the device is     still transferring packets. This can ultimately lead to a use-after-free issue. A malicious guest could     use this flaw to crash the QEMU process on the host, resulting in a denial of service condition, or     potentially execute arbitrary code within the context of the QEMU process on the host. This flaw affects     QEMU versions before 7.0.0. (CVE-2021-3750)

  - An off-by-one error was found in the SCSI device emulation in QEMU. It could occur while processing MODE     SELECT commands in mode_sense_page() if the 'page' argument was set to MODE_PAGE_ALLS (0x3f). A malicious     guest could use this flaw to potentially crash QEMU, resulting in a denial of service condition.
    (CVE-2021-3930)

  - A stack-buffer-overflow was found in QEMU in the NVME component. The flaw lies in nvme_changed_nslist()     where a malicious guest controlling certain input can read out of bounds memory. A malicious user could     use this flaw leading to disclosure of sensitive information. (CVE-2021-3947)

  - A NULL pointer dereference issue was found in the block mirror layer of QEMU in versions prior to 6.2.0.
    The `self` pointer is dereferenced in mirror_wait_on_conflicts() without ensuring that it's not NULL. A     malicious unprivileged user within the guest could use this flaw to crash the QEMU process on the host     when writing data reaches the threshold of mirroring node. (CVE-2021-4145)

  - A flaw was found in the QXL display device emulation in QEMU. An integer overflow in the cursor_alloc()     function can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer     overflow. This flaw allows a malicious privileged guest user to crash the QEMU process on the host or     potentially execute arbitrary code within the context of the QEMU process. (CVE-2021-4206)

  - A flaw was found in the QXL display device emulation in QEMU. A double fetch of guest controlled values     `cursor->header.width` and `cursor->header.height` can lead to the allocation of a small cursor object     followed by a subsequent heap-based buffer overflow. A malicious privileged guest user could use this flaw     to crash the QEMU process on the host or potentially execute arbitrary code within the context of the QEMU     process. (CVE-2021-4207)

  - A flaw was found in the virtio-net device of QEMU. This flaw was inadvertently introduced with the fix for     CVE-2021-3748, which forgot to unmap the cached virtqueue elements on error, leading to memory leakage and     other unexpected results. Affected QEMU version: 6.2.0. (CVE-2022-26353)

  - A flaw was found in the vhost-vsock device of QEMU. In case of error, an invalid element was not detached     from the virtqueue before freeing its memory, leading to memory leakage and other unexpected results.
    Affected QEMU versions <= 6.2.0. (CVE-2022-26354)

  -  Please review the referenced CVE identifiers for details.  (CVE-2021-3929)

  - QEMU: NULL pointer dereference in pci_write() in hw/acpi/pcihp.c (CVE-2021-4158)

  - QEMU: virtiofsd: potential privilege escalation via CVE-2018-13405 (CVE-2022-0358)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SUSE15 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2021:1942-1 advisory.

  - libslirp 4.0.0, as used in QEMU 4.1.0, has a use-after-free in ip_reass in ip_input.c. (CVE-2019-15890)

  - An out-of-bounds read/write access flaw was found in the USB emulator of the QEMU in versions before     5.2.0. This issue occurs while processing USB packets from a guest when USBDevice 'setup_len' exceeds its     'data_buf[4096]' in the do_token_in, do_token_out routines. This flaw allows a guest user to crash the     QEMU process, resulting in a denial of service, or the potential execution of arbitrary code with the     privileges of the QEMU process on the host. (CVE-2020-14364)

  - A heap-based buffer overflow was found in QEMU through 5.0.0 in the SDHCI device emulation support. It     could occur while doing a multi block SDMA transfer via the sdhci_sdma_transfer_multi_blocks() routine in     hw/sd/sdhci.c. A guest user or process could use this flaw to crash the QEMU process on the host,     resulting in a denial of service condition, or potentially execute arbitrary code with privileges of the     QEMU process on the host. (CVE-2020-17380)

  - QEMU 5.0.0 has a heap-based Buffer Overflow in flatview_read_continue in exec.c because hw/sd/sdhci.c     mishandles a write operation in the SDHC_BLKSIZE case. (CVE-2020-25085)

  - ** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. Reason: This candidate is a duplicate of CVE-2020-28916     (CVE-2020-25707)

  - A reachable assertion issue was found in the USB EHCI emulation code of QEMU. It could occur while     processing USB requests due to missing handling of DMA memory map failure. A malicious privileged user     within the guest may abuse this flaw to send bogus USB requests and crash the QEMU process on the host,     resulting in a denial of service. (CVE-2020-25723)

  - A flaw was found in the memory management API of QEMU during the initialization of a memory region cache.
    This issue could lead to an out-of-bounds write access to the MSI-X table while performing MMIO     operations. A guest user may abuse this flaw to crash the QEMU process on the host, resulting in a denial     of service. This flaw affects QEMU versions prior to 5.2.0. (CVE-2020-27821)

  - ncsi.c in libslirp through 4.3.1 has a buffer over-read because it tries to read a certain amount of     header data even if that exceeds the total packet length. (CVE-2020-29129)

  - slirp.c in libslirp through 4.3.1 has a buffer over-read because it tries to read a certain amount of     header data even if that exceeds the total packet length. (CVE-2020-29130)

  - In libslirp 4.1.0, as used in QEMU 4.2.0, tcp_subr.c misuses snprintf return values, leading to a buffer     overflow in later code. (CVE-2020-8608)

  - A flaw was found in the virtio-fs shared file system daemon (virtiofsd) of QEMU. The new 'xattrmap' option     may cause the 'security.capability' xattr in the guest to not drop on file write, potentially leading to a     modified, privileged executable in the guest. In rare circumstances, this flaw could be used by a     malicious user to elevate their privileges within the guest. (CVE-2021-20263)

  - The patch for CVE-2020-17380/CVE-2020-25085 was found to be ineffective, thus making QEMU vulnerable to     the out-of-bounds read/write access issues previously found in the SDHCI controller emulation code. This     flaw allows a malicious privileged guest to crash the QEMU process on the host, resulting in a denial of     service or potential code execution. QEMU up to (including) 5.2.0 is affected by this. (CVE-2021-3409)

  - A potential stack overflow via infinite loop issue was found in various NIC emulators of QEMU in versions     up to and including 5.2.0. The issue occurs in loopback mode of a NIC wherein reentrant DMA checks get     bypassed. A guest user/process may use this flaw to consume CPU cycles or crash the QEMU process on the     host resulting in DoS scenario. (CVE-2021-3416)

  - ** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: none. Reason: This candidate was withdrawn by     its CNA. Notes: none. (CVE-2021-3419)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLED15 / SLES15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2021:1942-1 advisory.

    - Switch method of splitting off hw-s390x-virtio-gpu-ccw.so as a module to what was accepted upstream     (bsc#1181103)
    - Fix OOB access in sdhci interface (CVE-2020-17380, bsc#1175144, CVE-2020-25085, bsc#1176681,     CVE-2021-3409, bsc#1182282)
    - Fix potential privilege escalation in virtiofsd tool (CVE-2021-20263, bsc#1183373)
    - Fix OOB access (stack overflow) in rtl8139 NIC emulation (CVE-2021-3416, bsc#1182968)
    - Fix heap overflow in MSIx emulation (CVE-2020-27821, bsc#1179686)
    - Fix package scripts to not use hard coded paths for temporary working directories and log files     (bsc#1182425)
    - QEMU BIOS fails to read stage2 loader on s390x (bsc#1186290)
    - For the record, these issues are fixed in this package already.
      Most are alternate references to previously mentioned issues:
      (CVE-2019-15890, bsc#1149813, CVE-2020-8608, bsc#1163019,       CVE-2020-14364, bsc#1175534, CVE-2020-25707, bsc#1178683,       CVE-2020-25723, bsc#1178935, CVE-2020-29130, bsc#1179477,       CVE-2020-29129, bsc#1179484, CVE-2021-3419, bsc#1182975)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
223628	Linux Distros Unpatched Vulnerability : CVE-2021-20263	Nessus	Misc.	low
191255	CentOS 9 : qemu-kvm-6.1.0-3.el9	Nessus	CentOS Local Security Checks	high
164115	GLSA-202208-27 : QEMU: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	high
151714	openSUSE 15 Security Update : qemu (openSUSE-SU-2021:1942-1)	Nessus	SuSE Local Security Checks	medium
150736	SUSE SLED15 / SLES15 Security Update : qemu (SUSE-SU-2021:1942-1)	Nessus	SuSE Local Security Checks	medium

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CVE-2021-20263

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