A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution (VM escape) as the QEMU process user.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-3241 advisory.

    hw/usb/hcd-xhci: Set reentrancy guard in timer functions (CVE-2026-17588)

    NOTE: Fixed by: https://gitlab.com/qemu-project/qemu/-/commit/1f24066fc88d33455ee54a20f29994d9e69997ba     (v11.1.0-rc3)NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/5fbd2fe1cc54259d045d00d4966aa2db1ba990d6 (v11.0.4) (CVE-2026-18054)

    NOTE: https://gitlab.com/qemu-project/qemu/-/work_items/3917NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/0be94d8d9c28e6b7235b34133d057090fe93be6c (v11.1.0-rc2)NOTE: Fixed by:
    https://gitlab.com/qemu-project/qemu/-/commit/88a0e5e45b41d407cf9adf1f2cf6f20f394a578d (v11.0.4)     (CVE-2026-50624)

    NOTE: Fixed by: https://gitlab.com/qemu-project/qemu/-/commit/733a98a552e4bd68932de1f58bd6ea39b57b261c     (v11.1.0-rc2)NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/6680c5612401c1eaa49eba134d14d374fefeb9d4 (v11.0.4) (CVE-2026-61402)

    NOTE: https://gitlab.com/qemu-project/qemu/-/work_items/3875NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/f404bf0e6504e0412a00ea64708f17d2a5e3f869 (v11.1.0-rc2)NOTE: Fixed by:
    https://gitlab.com/qemu-project/qemu/-/commit/a4abe1f1fa6f465b64fb400bea14c72bd5e32ac9 (v11.0.4)     (CVE-2026-61476)

    NOTE: Fixed by: https://gitlab.com/qemu-project/qemu/-/commit/b9d248dfaca5e31377ea4f7204aae788a050bafd     (v11.1.0-rc2)NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/82520d7759557062a5fae2211e3c79bbd5f01ed3 (v11.0.4) (CVE-2026-63110)

    Host-side AddressSanitizer heap-buffer-overflow READ in current QEMU master through the virtio-net-pci     receive filtering path on q35. The crash is in receive_filter(). (CVE-2026-63320)

    NOTE: Fixed by: https://gitlab.com/qemu-project/qemu/-/commit/a6e0519ea8ed6fc84fab9bf9ca82c7a55780f880     (v11.1.0-rc2)NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/52c7bb369b23dfcafb6e6d90665c777797b55e88 (v11.1.0-rc2)NOTE: Fixed by:
    https://gitlab.com/qemu-project/qemu/-/commit/f348425fddae38e0c1d6823501890acfb2a3bfb1 (v11.0.4)NOTE:
    Fixed by: https://gitlab.com/qemu-project/qemu/-/commit/9a06bb17256c0a38f0b53025bf804d2e2035f93f (v11.0.4)     (CVE-2026-63321)

    NOTE: https://gitlab.com/qemu-project/qemu/-/work_items/3607NOTE: Fixed by: https://gitlab.com/qemu-     project/qemu/-/commit/4727cc883b7e81d2c30b9801af54482d65b84292 (v11.1.0-rc2)NOTE: Fixed by:
    https://gitlab.com/qemu-project/qemu/-/commit/95b9a1bf26fef7c44f4925f78ade7fa824ed5e76 (v11.0.4)     (CVE-2026-63322)

    virtio-balloon: fix free-page BH teardown on unrealize (CVE-2026-66899)

    hw/net/virtio-net: strip trailing padding when caching RSC segment (CVE-2026-66900)

    hw/display/vga: fix text-mode OOB write after a graphics surface switch (CVE-2026-77913)

    A flaw was found in QEMU. The VAPIC setup hypercall in hw/i386/vapic.c does not validate that the writable     RAM alias remains within the option ROM window. A privileged guest user on a Q35/KVM machine can position     this alias over locked SMRAM, bypassing chipset D_LCK protection and injecting code into System Management     Mode memory. (CVE-2026-81627)

    io/channel-socket: do not treat a zero length write as an error (CVE-2026-84788)

    A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main     thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest     user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and     escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution     (VM escape) as the QEMU process user. (CVE-2026-93834)

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.

The version of qemu installed on the remote host is prior to 3.1.0-8. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-4027 advisory.

    hw/display/qxl: validate primary surface stride against width (CVE-2026-16271)

    hw/usb/hcd-xhci: Set reentrancy guard in timer functions (CVE-2026-17588)

    hw/display/vga: fix text-mode OOB write after a graphics surface switch (CVE-2026-77913)

    io/channel-socket: do not treat a zero length write as an error (CVE-2026-84788)

    A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main     thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest     user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and     escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution     (VM escape) as the QEMU process user. (CVE-2026-93834)

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.

The version of Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the TSSA-2026:1083 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-93834:
    A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main     thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest     user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and     escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution     (VM escape) as the QEMU process user.

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

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

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main
    thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest
    user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and
    escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution
    (VM escape) as the QEMU process user. (CVE-2026-93834)

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

  - A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main     thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest     user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and     escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution     (VM escape) as the QEMU process user. (CVE-2026-93834)

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

ID	Name	Product	Family	Type	Severity
371849	Amazon Linux 2023 : qemu, qemu-common, qemu-guest-agent (ALAS2023-2026-3241)	Nessus	Amazon Linux Local Security Checks	Local	high
371773	Amazon Linux 2 : qemu (ALAS-2026-4027)	Nessus	Amazon Linux Local Security Checks	Local	high
365156	TencentOS Server 4: qemu (TSSA-2026:1083)	Nessus	Tencent Local Security Checks	Local	high
473220	Echo: qemu: security update to 1:10.0.13+ds-0+deb13u1+e3	Tenable Cloud Security	Echo Local Security Checks	Local	high
473220	Echo: qemu: security update to 1:10.0.13+ds-0+deb13u1+e3	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
350663	Linux Distros Unpatched Vulnerability : CVE-2026-93834	Nessus	Misc.	Local	high

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CVE-2026-93834

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