Amazon Linux 2 : qemu (ALAS-2026-4009)

high Nessus Plugin ID 371765

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

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 ALAS2-2026-4009 advisory.

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: 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)

QEMU's 9pfs readonly check at line 2108-2109 tests mode & O_TRUNC and mode & O_APPEND against the raw 9P open mode byte. For the 9P2000.u protocol, mode uses 9P flag values (Otrunc=0x10, Oappend=0x80), but the check compares against Linux constants (O_TRUNC=0x200, O_APPEND=0x400). Since 0x10 & 0x200 = 0 and 0x80 & 0x400 = 0, both flags bypass the readonly guard. The mode is then correctly converted to host flags via omode_to_uflags(), so open() is called with O_TRUNC -- truncating host files on readonly shares.9P2000.L is NOT affected (guest passes Linux flags directly, so the bit values match). (CVE-2026-63318)

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: 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)

NOTE: https://gitlab.com/qemu-project/qemu/-/work_items/3846NOTE: Fixed by: https://gitlab.com/qemu- project/qemu/-/commit/370882d0869567e5f21b95229a763171e319d0db (v11.1.0-rc3)NOTE: Fixed by:
https://gitlab.com/qemu-project/qemu/-/commit/e00b9c9193de00f5782cb919d91eb80d255017fe (v11.0.4) (CVE-2026-65928)

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)

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.

Solution

Run 'yum update qemu' or or 'yum update --advisory ALAS2-2026-4009' to update your system.

Plugin Details

Severity: High

ID: 371765

File Name: al2_ALAS-2026-4009.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 10/24/2026

Updated: 10/24/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 93.19

CVSS v2

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 4.8

Vector: CVSS2#AV:L/AC:L/Au:M/C:C/I:C/A:C

CVSS Score Source: CVE-2026-81627

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

Vector: CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:ivshmem-tools, p-cpe:/a:amazon:linux:qemu-audio-alsa, p-cpe:/a:amazon:linux:qemu-audio-oss, p-cpe:/a:amazon:linux:qemu-audio-pa, p-cpe:/a:amazon:linux:qemu-audio-sdl, p-cpe:/a:amazon:linux:qemu-block-curl, p-cpe:/a:amazon:linux:qemu-block-dmg, p-cpe:/a:amazon:linux:qemu-block-iscsi, p-cpe:/a:amazon:linux:qemu-block-nfs, p-cpe:/a:amazon:linux:qemu-block-rbd, p-cpe:/a:amazon:linux:qemu-block-ssh, p-cpe:/a:amazon:linux:qemu-common, p-cpe:/a:amazon:linux:qemu-debuginfo, p-cpe:/a:amazon:linux:qemu-guest-agent, p-cpe:/a:amazon:linux:qemu-img, p-cpe:/a:amazon:linux:qemu-kvm-core, p-cpe:/a:amazon:linux:qemu-kvm, p-cpe:/a:amazon:linux:qemu-system-aarch64-core, p-cpe:/a:amazon:linux:qemu-system-aarch64, p-cpe:/a:amazon:linux:qemu-system-x86-core, p-cpe:/a:amazon:linux:qemu-system-x86, p-cpe:/a:amazon:linux:qemu-ui-curses, p-cpe:/a:amazon:linux:qemu-ui-gtk, p-cpe:/a:amazon:linux:qemu-ui-sdl, p-cpe:/a:amazon:linux:qemu-user-binfmt, p-cpe:/a:amazon:linux:qemu-user-static, p-cpe:/a:amazon:linux:qemu-user, p-cpe:/a:amazon:linux:qemu

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 10/24/2026

Vulnerability Publication Date: 9/18/2026

Reference Information

CVE: CVE-2026-18054, CVE-2026-50624, CVE-2026-61476, CVE-2026-63318, CVE-2026-63320, CVE-2026-63322, CVE-2026-65928, CVE-2026-81627

IAVB: 2026-B-0284

Detections

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