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

  - A NULL pointer dereference flaw was found in the Linux kernel's GPU Nouveau driver functionality in     versions prior to 5.12-rc1 in the way the user calls ioctl DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC. This flaw     allows a local user to crash the system. (CVE-2020-25639)

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

The remote Ubuntu 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4949-1 advisory.

    Ryota Shiga discovered that the eBPF implementation in the Linux kernel did not properly verify that a BPF     program only reserved as much memory for a ring buffer as was allocated. A local attacker could use this     to cause a denial of service (system crash) or execute arbitrary code. (CVE-2021-3489)

    Manfred Paul discovered that the eBPF implementation in the Linux kernel did not properly track bounds on     bitwise operations. A local attacker could use this to cause a denial of service (system crash) or execute     arbitrary code. (CVE-2021-3490)

    Billy Jheng Bing-Jhong discovered that the io_uring implementation of the Linux kernel did not properly     enforce the MAX_RW_COUNT limit in some situations. A local attacker could use this to cause a denial of     service (system crash) or execute arbitrary code. (CVE-2021-3491)

    It was discovered that the Nouveau GPU driver in the Linux kernel did not properly handle error conditions     in some situations. A local attacker could use this to cause a denial of service (system crash).
    (CVE-2020-25639)

    Olivier Benjamin, Norbert Manthey, Martin Mazein, and Jan H. Schnherr discovered that the Xen     paravirtualization backend in the Linux kernel did not properly propagate errors to frontend drivers in     some situations. An attacker in a guest VM could possibly use this to cause a denial of service (host     domain crash). (CVE-2021-26930)

    Jan Beulich discovered that multiple Xen backends in the Linux kernel did not properly handle certain     error conditions under paravirtualization. An attacker in a guest VM could possibly use this to cause a     denial of service (host domain crash). (CVE-2021-26931)

    It was discovered that the fastrpc driver in the Linux kernel did not prevent user space applications from     sending kernel RPC messages. A local attacker could possibly use this to gain elevated privileges.
    (CVE-2021-28375)

    It was discovered that the Freescale Gianfar Ethernet driver for the Linux kernel did not properly handle     receive queue overrun when jumbo frames were enabled in some situations. An attacker could use this to     cause a denial of service (system crash). (CVE-2021-29264)

    It was discovered that the USB/IP driver in the Linux kernel contained race conditions during the update     of local and shared status. An attacker could use this to cause a denial of service (system crash).
    (CVE-2021-29265)

    It was discovered that the vDPA backend virtio driver in the Linux kernel contained a use-after-free     vulnerability. An attacker could use this to cause a denial of service (system crash) or possibly execute     arbitrary code. (CVE-2021-29266)

    It was discovered that the TIPC protocol implementation in the Linux kernel did not properly validate     passed encryption key sizes. A local attacker could use this to cause a denial of service (system crash).
    (CVE-2021-29646)

    It was discovered that a race condition existed in the netfilter subsystem of the Linux kernel when     replacing tables. A local attacker could use this to cause a denial of service (system crash).
    (CVE-2021-29650)

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

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

The SUSE Linux Enterprise 12 SP5 Azure kernel was updated to receive various security and bugfixes.

The following security bugs were fixed :

CVE-2021-3347: A use-after-free was discovered in the PI futexes during fault handling, allowing local users to execute code in the kernel (bnc#1181349).

CVE-2021-20177: Fixed a kernel panic related to iptables string matching rules. A privileged user could insert a rule which could lead to denial of service (bnc#1180765).

CVE-2021-0342: In tun_get_user of tun.c, there is possible memory corruption due to a use after free. This could lead to local escalation of privilege with System execution privileges required.
(bnc#1180812)

CVE-2020-27835: A use-after-free in the infiniband hfi1 driver was found, specifically in the way user calls Ioctl after open dev file and fork. A local user could use this flaw to crash the system (bnc#1179878).

CVE-2020-25639: Fixed a NULL pointer dereference via nouveau ioctl (bnc#1176846).

CVE-2020-29569: Fixed a potential privilege escalation and information leaks related to the PV block backend, as used by Xen (bnc#1179509).

CVE-2020-29568: Fixed a denial of service issue, related to processing watch events (bnc#1179508).

CVE-2020-36158: Fixed an issue wich might have allowed a remote attackers to execute arbitrary code via a long SSID value in mwifiex_cmd_802_11_ad_hoc_start() (bnc#1180559).

CVE-2020-28374: Fixed a vulnerability caused by insufficient identifier checking in the LIO SCSI target code. This could have been used by a remote attackers to read or write files via directory traversal in an XCOPY request (bnc#1178372).

The update package also includes non-security fixes. See advisory for details.

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The SUSE Linux Enterprise 15 SP2 realtime kernel was updated to receive various security and bugfixes.

The following security bugs were fixed :

CVE-2021-3347: A use-after-free was discovered in the PI futexes during fault handling, allowing local users to execute code in the kernel (bnc#1181349).

CVE-2021-3348: Fixed a use-after-free in nbd_add_socket that could be triggered by local attackers (with access to the nbd device) via an I/O request at a certain point during device setup (bnc#1181504).

CVE-2021-20177: Fixed a kernel panic related to iptables string matching rules. A privileged user could insert a rule which could lead to denial of service (bnc#1180765).

CVE-2021-0342: In tun_get_user of tun.c, there is possible memory corruption due to a use after free. This could lead to local escalation of privilege with System execution privileges required.
(bnc#1180812)

CVE-2020-27835: A use-after-free in the infiniband hfi1 driver was found, specifically in the way user calls Ioctl after open dev file and fork. A local user could use this flaw to crash the system (bnc#1179878).

CVE-2020-25639: Fixed a NULL pointer dereference via nouveau ioctl (bnc#1176846).

CVE-2020-29569: Fixed a potential privilege escalation and information leaks related to the PV block backend, as used by Xen (bnc#1179509).

CVE-2020-29568: Fixed a denial of service issue, related to processing watch events (bnc#1179508).

CVE-2020-25211: Fixed a flaw where a local attacker was able to inject conntrack netlink configuration that could cause a denial of service or trigger the use of incorrect protocol numbers in ctnetlink_parse_tuple_filter (bnc#1176395).

CVE-2020-28374: Fixed a Linux SCSI target issue (bsc#1178372).

The update package also includes non-security fixes. See advisory for details.

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the versions of the kernel packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

  - An issue was discovered in the Linux kernel through     5.11.3. A kernel pointer leak can be used to determine     the address of the iscsi_transport structure. When an     iSCSI transport is registered with the iSCSI subsystem,     the transport's handle is available to unprivileged     users via the sysfs file system, at     /sys/class/iscsi_transport/$TRANSPORT_NAME/handle. When     read, the show_transport_handle function (in     drivers/scsi/scsi_transport_iscsi.c) is called, which     leaks the handle. This handle is actually the pointer     to an iscsi_transport struct in the kernel module's     global variables.(CVE-2021-27363)

  - An issue was discovered in the Linux kernel through     5.11.3. Certain iSCSI data structures do not have     appropriate length constraints or checks, and can     exceed the PAGE_SIZE value. An unprivileged user can     send a Netlink message that is associated with iSCSI,     and has a length up to the maximum length of a Netlink     message.(CVE-2021-27365)

  - An issue was discovered in the Linux kernel through     5.11.3. drivers/scsi/scsi_transport_iscsi.c is     adversely affected by the ability of an unprivileged     user to craft Netlink messages.(CVE-2021-27364)

  - Overlayfs did not properly perform permission checking     when copying up files in an overlayfs and could be     exploited from within a user namespace, if, for     example, unprivileged user namespaces were allowed. It     was possible to have a file not readable by an     unprivileged user to be copied to a mountpoint     controlled by the user, like a removable device. This     was introduced in kernel version 4.19 by commit d1d04ef     ('ovl: stack file ops'). This was fixed in kernel     version 5.8 by commits 56230d9 ('ovl: verify     permissions in ovl_path_open()'), 48bd024 ('ovl: switch     to mounter creds in readdir') and 05acefb ('ovl: check     permission to open real file'). Additionally, commits     130fdbc ('ovl: pass correct flags for opening real     directory') and 292f902 ('ovl: call secutiry hook in     ovl_real_ioctl()') in kernel 5.8 might also be desired     or necessary. These additional commits introduced a     regression in overlay mounts within user namespaces     which prevented access to files with ownership outside     of the user namespace. This regression was mitigated by     subsequent commit b6650da ('ovl: do not fail because of     O_NOATIMEi') in kernel 5.11.(CVE-2020-16120)

  - A flaw was found in the Linux kernel's implementation     of string matching within a packet. A privileged user     (with root or CAP_NET_ADMIN) when inserting iptables     rules could insert a rule which can panic the     system.(CVE-2021-20177)

  - fs/nfsd/nfs3xdr.c in the Linux kernel through 5.10.8,     when there is an NFS export of a subdirectory of a     filesystem, allows remote attackers to traverse to     other parts of the filesystem via READDIRPLUS. NOTE:
    some parties argue that such a subdirectory export is     not intended to prevent this attack see also the     exports(5) no_subtree_check default     behavior.(CVE-2021-3178)

  - nbd_add_socket in drivers/block/nbd.c in the Linux     kernel through 5.10.12 has an ndb_queue_rq     use-after-free that could be triggered by local     attackers (with access to the nbd device) via an I/O     request at a certain point during device setup, aka     CID-b98e762e3d71.(CVE-2021-3348)

  - An issue was discovered in the Linux kernel through     5.10.11. PI futexes have a kernel stack use-after-free     during fault handling, allowing local users to execute     code in the kernel, aka     CID-34b1a1ce1458.(CVE-2021-3347)

  - A flaw use after free in the Linux kernel TUN/TAP     device driver functionality was found in the way user     create and use tun/tap device. A local user could use     this flaw to crash the system or possibly escalate     their privileges on the system.(CVE-2021-0342)

  - A flaw was found in the Linux kernel. A use-after-free     memory flaw was found in the perf subsystem allowing a     local attacker with permission to monitor perf events     to corrupt memory and possibly escalate privileges. The     highest threat from this vulnerability is to data     confidentiality and integrity as well as system     availability.(CVE-2020-14351)

  - A flaw was found in the Linux kernel's multi-touch     input system. An out-of-bounds write triggered by a     use-after-free issue could lead to memory corruption or     possible privilege escalation. The highest threat from     this vulnerability is to confidentiality, integrity, as     well as system availability.(CVE-2020-0465)

  - A NULL pointer dereference flaw was found in the Linux     kernel's GPU Nouveau driver functionality in the way     the user calls ioctl DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC.
    This flaw allows a local user to crash the     system.(CVE-2020-25639)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The version of kernel installed on the remote host is prior to 5.4.105-48.177. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2KERNEL-5.4-2022-001 advisory.

    A NULL pointer dereference flaw was found in the Linux kernel's GPU Nouveau driver functionality in the     way the user calls ioctl DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC. This flaw allows a local user to crash the     system. (CVE-2020-25639)

    An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to     the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be     encountered. In one case, an error encountered earlier might be discarded by later processing, resulting     in the caller assuming successful mapping, and hence subsequent operations trying to access space that     wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery     from the error. This affects drivers/block/xen-blkback/blkback.c. (CVE-2021-26930)

    An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI     backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially     being at least under the influence of guests (such as out of memory conditions), it isn't correct to     assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running     in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.
    (CVE-2021-26931)

    An issue was discovered in the Linux kernel 3.2 through 5.10.16, as used by Xen. Grant mapping operations     often occur in batch hypercalls, where a number of operations are done in a single hypercall, the success     or failure of each one is reported to the backend driver, and the backend driver then loops over the     results, performing follow-up actions based on the success or failure of each operation. Unfortunately,     when running in PV mode, the Linux backend drivers mishandle this: Some errors are ignored, effectively     implying their success from the success of related batch elements. In other cases, errors resulting from     one batch element lead to further batch elements not being inspected, and hence successful ones to not be     possible to properly unmap upon error recovery. Only systems with Linux backends running in PV mode are     vulnerable. Linux backends run in HVM / PVH modes are not vulnerable. This affects arch/*/xen/p2m.c and     drivers/xen/gntdev.c. (CVE-2021-26932)

    A flaw was found in the way access to sessions and handles was handled in the iSCSI driver in the Linux     kernel. A local user could use this flaw to leak iSCSI transport handle kernel address or end arbitrary     iSCSI connections on the system. (CVE-2021-27363)

    A flaw was found in the Linux kernel. An out-of-bounds read was discovered in the libiscsi module that     could lead to reading kernel memory or a crash. The highest threat from this vulnerability is to data     confidentiality as well as system availability. (CVE-2021-27364)

    A flaw was found in the Linux kernel. A heap buffer overflow in the iSCSI subsystem is triggered by     setting an iSCSI string attribute to a value larger than one page and then trying to read it. The highest     threat from this vulnerability is to data confidentiality and integrity as well as system availability.
    (CVE-2021-27365)

    An issue was discovered in the Linux kernel through 5.11.3, as used with Xen PV. A certain part of the     netback driver lacks necessary treatment of errors such as failed memory allocations (as a result of     changes to the handling of grant mapping errors). A host OS denial of service may occur during misbehavior     of a networking frontend driver. NOTE: this issue exists because of an incomplete fix for CVE-2021-26931.
    (CVE-2021-28038)

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

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

An update of the linux package has been released.

ID	Name	Product	Family	Published	Updated	Severity
229957	Linux Distros Unpatched Vulnerability : CVE-2020-25639	Nessus	Misc.	3/5/2025	7/17/2026	medium
149411	Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-4949-1)	Nessus	Ubuntu Local Security Checks	5/12/2021	8/27/2024	high
146362	SUSE SLES12 Security Update : kernel (SUSE-SU-2021:0348-1)	Nessus	SuSE Local Security Checks	2/10/2021	1/22/2024	high
146406	SUSE SLES15 Security Update : kernel (SUSE-SU-2021:0427-1)	Nessus	SuSE Local Security Checks	2/11/2021	1/22/2024	high
148604	EulerOS Virtualization 2.9.0 : kernel (EulerOS-SA-2021-1751)	Nessus	Huawei Local Security Checks	4/15/2021	1/4/2024	high
160419	Amazon Linux 2 : kernel (ALASKERNEL-5.4-2022-001)	Nessus	Amazon Linux Local Security Checks	5/2/2022	2/26/2026	high
148350	Photon OS 4.0: Linux PHSA-2021-4.0-0007	Nessus	PhotonOS Local Security Checks	4/7/2021	11/13/2025	high
145287	openSUSE Security Update : the Linux Kernel (openSUSE-2021-75)	Nessus	SuSE Local Security Checks	1/25/2021	2/9/2023	critical

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