Vulnerability in Linux kernel (CVE-2026-43249)
Summary
Vulnerability in Linux kernel (CVE-2026-43249). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
9p/xen: protect xen_9pfs_front_free against concurrent calls
The xenwatch thread can race with other back-end change notifications
and call xen_9pfs_front_free() twice, hitting the observed general
protection fault due to a double-free. Guard the teardown path so only
one caller can release the front-end state at a time, preventing the
crash.
This is a fix for the following double-free:
[ 27.052347] Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] SMP DEBUG_PAGEALLOC NOPTI
[ 27.052357] CPU: 0 UID: 0 PID: 32 Comm: xenwatch Not tainted 6.18.0-02087-g51ab33fc0a8b-dirty #60 PREEMPT(none)
[ 27.052363] RIP: e030:xen_9pfs_front_free+0x1d/0x150
[ 27.052368] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 41 55 41 54 55 48 89 fd 48 c7 c7 48 d0 92 85 53 e8 cb cb 05 00 48 8b 45 08 48 8b 55 00 <48> 3b 28 0f 85 f9 28 35 fe 48 3b 6a 08 0f 85 ef 28 35 fe 48 89 42
[ 27.052377] RSP: e02b:ffffc9004016fdd0 EFLAGS: 00010246
[ 27.052381] RAX: 6b6b6b6b6b6b6b6b RBX: ffff88800d66e400 RCX: 0000000000000000
[ 27.052385] RDX: 6b6b6b6b6b6b6b6b RSI: 0000000000000000 RDI: 0000000000000000
[ 27.052389] RBP: ffff88800a887040 R08: 0000000000000000 R09: 0000000000000000
[ 27.052393] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888009e46b68
[ 27.052397] R13: 0000000000000200 R14: 0000000000000000 R15: ffff88800a887040
[ 27.052404] FS: 0000000000000000(0000) GS:ffff…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-43249 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-43249" on the vendor's site.
CVE-2026-43249 (Linux kernel) — CWE-415 / CVSS v3 8.8
Attack vector: adjacent-network / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-415) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-43249 linux-lts Fixed in: 6.12.80-r0
- Debian DEBIAN-CVE-2026-43249 linux
- Ubuntu UBUNTU-CVE-2026-43249 linux
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com