The fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative Return Stack Overflow) are not IRQ-safe. It was believed that the mitigations always operated in contexts with IRQs disabled. However, the original XSA-254 fix for Meltdown (XPTI) deliberately left interrupts enabled on two entry paths; one unconditionally, and one conditionally on whether XPTI was active. As BTC/SRSO and Meltdown affect different CPU vendors, the mitigations are not active together by default. Therefore, there is a race condition whereby a malicious PV guest can bypass BTC/SRSO protections and launch a BTC/SRSO attack against Xen.

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - The current setup of the quarantine page tables assumes that the quarantine domain (dom_io) has been
    initialized with an address width of DEFAULT_DOMAIN_ADDRESS_WIDTH (48) and hence 4 page table levels.
    However dom_io being a PV domain gets the AMD-Vi IOMMU page tables levels based on the maximum (hot
    pluggable) RAM address, and hence on systems with no RAM above the 512GB mark only 3 page-table levels are
    configured in the IOMMU. On systems without RAM above the 512GB boundary amd_iommu_quarantine_init() will
    setup page tables for the scratch page with 4 levels, while the IOMMU will be configured to use 3 levels
    only, resulting in the last page table directory (PDE) effectively becoming a page table entry (PTE), and
    hence a device in quarantine mode gaining write access to the page destined to be a PDE. Due to this page
    table level mismatch, the sink page the device gets read/write access to is no longer cleared between
    device assignment, possibly leading to data leaks. (CVE-2023-46835)

  - The fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative Return Stack Overflow) are not IRQ-
    safe. It was believed that the mitigations always operated in contexts with IRQs disabled. However, the
    original XSA-254 fix for Meltdown (XPTI) deliberately left interrupts enabled on two entry paths; one
    unconditionally, and one conditionally on whether XPTI was active. As BTC/SRSO and Meltdown affect
    different CPU vendors, the mitigations are not active together by default. Therefore, there is a race
    condition whereby a malicious PV guest can bypass BTC/SRSO protections and launch a BTC/SRSO attack
    against Xen. (CVE-2023-46836)

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

  - The fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative Return Stack Overflow) are not IRQ-     safe. It was believed that the mitigations always operated in contexts with IRQs disabled. However, the     original XSA-254 fix for Meltdown (XPTI) deliberately left interrupts enabled on two entry paths; one     unconditionally, and one conditionally on whether XPTI was active. As BTC/SRSO and Meltdown affect     different CPU vendors, the mitigations are not active together by default. Therefore, there is a race     condition whereby a malicious PV guest can bypass BTC/SRSO protections and launch a BTC/SRSO attack     against Xen. (CVE-2023-46836)

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

The remote host is affected by the vulnerability described in GLSA-202409-10 (Xen: Multiple Vulnerabilities)

    Multiple vulnerabilities have been discovered in Xen. Please review the CVE identifiers referenced below     for details.

Tenable has extracted the preceding description block directly from the Gentoo Linux 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 remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 / openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4945-1 advisory.

    - CVE-2023-46836: Fixed BTC/SRSO fixes not fully effective (bsc#1216807).
    - CVE-2023-46835: Fixed mismatch in IOMMU quarantine page table levels on x86/AMD (bsc#1216654).

    Update to Xen 4.17.3 bug fix release (bsc#1027519).

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.

The remote Fedora 37 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2023-e62da41072 advisory.

    x86/AMD: mismatch in IOMMU quarantine page table levels [XSA-445,     CVE-2023-46835]     x86: BTC/SRSO fixes not fully effective [XSA-446, CVE-2023-46836]

Tenable has extracted the preceding description block directly from the Fedora 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 remote Fedora 38 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2023-56901a79a1 advisory.

    x86/AMD: mismatch in IOMMU quarantine page table levels [XSA-445,     CVE-2023-46835]     x86: BTC/SRSO fixes not fully effective [XSA-446, CVE-2023-46836]

Tenable has extracted the preceding description block directly from the Fedora 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 remote Fedora 39 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2023-fa01e4c6ba advisory.

    x86/AMD: mismatch in IOMMU quarantine page table levels [XSA-445,     CVE-2023-46835]     x86: BTC/SRSO fixes not fully effective [XSA-446, CVE-2023-46836]

Tenable has extracted the preceding description block directly from the Fedora 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 fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative Return Stack Overflow) are not IRQ-safe as it was believed that the mitigations were always operated in contexts with IRQs disabled. However due to an unanticipated interaction with XSA-254 (Meltdown), a race condition exists whereby a malicious guest can bypass BTC/SRSO protections.
As a result, an attacker in a PV guest can infer the contents of memory belonging to other guests.

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 SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4484-1 advisory.

    - CVE-2023-46835: x86/AMD: mismatch in IOMMU quarantine page table levels (XSA-445) (bsc#1216654).
    - CVE-2023-46836: x86: BTC/SRSO fixes not fully effective (XSA-446) (bsc#1216807).

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.

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4485-1 advisory.

    - CVE-2023-46835: x86/AMD: mismatch in IOMMU quarantine page table levels (XSA-445) (bsc#1216654).
    - CVE-2023-46836: x86: BTC/SRSO fixes not fully effective (XSA-446) (bsc#1216807).

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.

The remote SUSE Linux SLES12 / SLES_SAP12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4486-1 advisory.

    - CVE-2023-46835: x86/AMD: mismatch in IOMMU quarantine page table levels (XSA-445) (bsc#1216654).
    - CVE-2023-46836: x86: BTC/SRSO fixes not fully effective (XSA-446) (bsc#1216807).

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.

The remote openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4476-1 advisory.

  - A division-by-zero error on some AMD processors can potentially return speculative data resulting in loss     of confidentiality. (CVE-2023-20588)

  - arm32: The cache may not be properly cleaned/invalidated [XSA-437, CVE-2023-34321] top-level shadow     reference dropped too early for 64-bit PV guests [XSA-438, CVE-2023-34322] x86/AMD: Divide speculative     information leak [XSA-439, CVE-2023-20588] (CVE-2023-34322)

  - The vulnerability exists due to insufficient validation of user-supplied input in libfsimage. A remote     guest can use pygrab to trigger stack-based buffer overflow and execute arbitrary code on the host system     (CVE-2023-34325)

  - The vulnerability exists due to missing IOMMU TLB flushing on x86/AMD systems. A malicious guest can     access memory not owned by the guest and escalate privileges on the system. (CVE-2023-34326)

  - The vulnerability exists due to improper validation of guest state when using Debug Masks in HVM vCPU. A     malicious guest can perform a denial of service (DoS) attack against the guest OS. (CVE-2023-34327)

  - The vulnerability exists due to improper validation of guest state in PV vCPU. A malicious guest place a     breakpoint over the live GDT and perform a denial of service (DoS) attack against the host.
    (CVE-2023-34328)

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

The remote openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4475-1 advisory.

  - A division-by-zero error on some AMD processors can potentially return speculative data resulting in loss     of confidentiality. (CVE-2023-20588)

  - arm32: The cache may not be properly cleaned/invalidated [XSA-437, CVE-2023-34321] top-level shadow     reference dropped too early for 64-bit PV guests [XSA-438, CVE-2023-34322] x86/AMD: Divide speculative     information leak [XSA-439, CVE-2023-20588] (CVE-2023-34322)

  - The vulnerability exists due to insufficient validation of user-supplied input in libfsimage. A remote     guest can use pygrab to trigger stack-based buffer overflow and execute arbitrary code on the host system     (CVE-2023-34325)

  - The vulnerability exists due to missing IOMMU TLB flushing on x86/AMD systems. A malicious guest can     access memory not owned by the guest and escalate privileges on the system. (CVE-2023-34326)

  - The vulnerability exists due to improper validation of guest state when using Debug Masks in HVM vCPU. A     malicious guest can perform a denial of service (DoS) attack against the guest OS. (CVE-2023-34327)

  - The vulnerability exists due to improper validation of guest state in PV vCPU. A malicious guest place a     breakpoint over the live GDT and perform a denial of service (DoS) attack against the host.
    (CVE-2023-34328)

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 SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2023:4466-1 advisory.

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

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - The caching invalidation guidelines from the AMD-Vi specification (48882—Rev 3.07-PUB—Oct 2022) is
    incorrect on some hardware, as devices will malfunction (see stale DMA mappings) if some fields of the DTE
    are updated but the IOMMU TLB is not flushed. Such stale DMA mappings can point to memory ranges not owned
    by the guest, thus allowing access to unindented memory regions. (CVE-2023-34326)

  - When a transaction is committed, C Xenstored will first check the quota is correct before attempting to
    commit any nodes. It would be possible that accounting is temporarily negative if a node has been removed
    outside of the transaction. Unfortunately, some versions of C Xenstored are assuming that the quota cannot
    be negative and are using assert() to confirm it. This will lead to C Xenstored crash when tools are built
    without -DNDEBUG (this is the default). (CVE-2023-34323)

  - [This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities
    correspond to which CVE.] libfsimage contains parsing code for several filesystems, most of them based on
    grub-legacy code. libfsimage is used by pygrub to inspect guest disks. Pygrub runs as the same user as the
    toolstack (root in a priviledged domain). At least one issue has been reported to the Xen Security Team
    that allows an attacker to trigger a stack buffer overflow in libfsimage. After further analisys the Xen
    Security Team is no longer confident in the suitability of libfsimage when run against guest controlled
    input with super user priviledges. In order to not affect current deployments that rely on pygrub patches
    are provided in the resolution section of the advisory that allow running pygrub in deprivileged mode.
    CVE-2023-4949 refers to the original issue in the upstream grub project ("An attacker with local access to
    a system (either through a disk or external drive) can present a modified XFS partition to grub-legacy in
    such a way to exploit a memory corruption in grub’s XFS file system implementation.") CVE-2023-34325
    refers specifically to the vulnerabilities in Xen's copy of libfsimage, which is decended from a very old
    version of grub. (CVE-2023-34325)

  - [This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities
    correspond to which CVE.] AMD CPUs since ~2014 have extensions to normal x86 debugging functionality. Xen
    supports guests using these extensions. Unfortunately there are errors in Xen's handling of the guest
    state, leading to denials of service. 1) CVE-2023-34327 - An HVM vCPU can end up operating in the context
    of a previous vCPUs debug mask state. 2) CVE-2023-34328 - A PV vCPU can place a breakpoint over the live
    GDT. This allows the PV vCPU to exploit XSA-156 / CVE-2015-8104 and lock up the CPU entirely.
    (CVE-2023-34327)

ID	Name	Product	Family	Severity
424698	Alpine: multiple xen packages: security update to 4.17.2-r4	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
424698	Alpine: multiple xen packages: security update to 4.17.2-r4	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium
227355	Linux Distros Unpatched Vulnerability : CVE-2023-46836	Nessus	Misc.	medium
207559	GLSA-202409-10 : Xen: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	high
187177	SUSE SLED15: xen / xen-devel / xen-doc-html / xen-libs / xen-libs-32bit / etc (SUSE-SU-2023:4945-1)	Nessus	SuSE Local Security Checks	medium
408171	Alpine: xen: security update to 4.16.5-r4	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
408171	Alpine: xen: security update to 4.16.5-r4	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium
186496	Fedora 37 : xen (2023-e62da41072)	Nessus	Fedora Local Security Checks	medium
186460	Fedora 38 : xen (2023-56901a79a1)	Nessus	Fedora Local Security Checks	medium
186457	Fedora 39 : xen (2023-fa01e4c6ba)	Nessus	Fedora Local Security Checks	medium
186415	Xen: x86: BTC/SRSO Fixes Not Fully Effective (XSA-446)	Nessus	Misc.	medium
186026	SUSE SLES15: xen / xen-devel / xen-libs / xen-tools / xen-tools-domU / etc (SUSE-SU-2023:4484-1)	Nessus	SuSE Local Security Checks	medium
186023	SUSE SLES15 Security Update : xen (SUSE-SU-2023:4485-1)	Nessus	SuSE Local Security Checks	medium
186022	SUSE SLES12: xen / xen-devel / xen-doc-html / xen-libs / xen-libs-32bit / etc (SUSE-SU-2023:4486-1)	Nessus	SuSE Local Security Checks	medium
185977	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : xen (SUSE-SU-2023:4476-1)	Nessus	SuSE Local Security Checks	high
185975	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : xen (SUSE-SU-2023:4475-1)	Nessus	SuSE Local Security Checks	high
185936	SUSE SLES15 Security Update : xen (SUSE-SU-2023:4466-1)	Nessus	SuSE Local Security Checks	medium
408022	Alpine: xen: security update to 4.17.2-r4	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
408022	Alpine: xen: security update to 4.17.2-r4	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium
407827	Alpine: xen: security update to 4.15.5-r3	Tenable Cloud Security	Alpine Linux Local Security Checks	high
407827	Alpine: xen: security update to 4.15.5-r3	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	high

Detections

Analytics

CVE-2023-46836

medium

Tenable Plugins

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