Use-After-Free in Linux kernel (CVE-2026-43237)
Summary
Vulnerability in Linux kernel (CVE-2026-43237). 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:
drm/amdgpu: Refactor amdgpu_gem_va_ioctl for Handling Last Fence Update and Timeline Management v4
This commit simplifies the amdgpu_gem_va_ioctl function, key updates
include:
- Moved the logic for managing the last update fence directly into
amdgpu_gem_va_update_vm. - Introduced checks for the timeline point to enable conditional
replacement or addition of fences.
v2: Addressed review comments from Christian.
v3: Updated comments (Christian).
v4: The previous version selected the fence too early and did not manage its
reference correctly, which could lead to stale or freed fences being used.
This resulted in refcount underflows and could crash when updating GPU
timelines.
The fence is now chosen only after the VA mapping work is completed, and its
reference is taken safely. After exporting it to the VM timeline syncobj, the
driver always drops its local fence reference, ensuring balanced refcounting
and avoiding use-after-free on dma_fence.
Crash signature:
[ 205.828135] refcount_t: underflow; use-after-free.
[ 205.832963] WARNING: CPU: 30 PID: 7274 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110
...
[ 206.074014] Call Trace:
[ 206.076488]
[ 206.078608] amdgpu_gem_va_ioctl+0x6ea/0x740 [amdgpu]
[ 206.084040] ? __pfx_amdgpu_gem_va_ioctl+0x10/0x10 [amdgpu]
[ 206.089994] drm_ioctl_kernel+0x86/0xe0 [drm]
[ 206.094415] drm_ioctl+0x26e/0x520 [d…
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-2026-43237 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-43237" on the vendor's site.
CVE-2026-43237 (Linux kernel) — CWE-416 / CVSS v3 7.8
Attack vector: local / 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.
Use-after-free (CWE-416) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 7.8/10). 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-2026-43237 linux-lts Fixed in: 6.18.35-r1
- Debian DEBIAN-CVE-2026-43237 linux Fixed in: 6.19.6-1
- Ubuntu UBUNTU-CVE-2026-43237 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 github.com