Use-After-Free in Linux kernel (CVE-2025-39944)
Summary
Vulnerability in Linux kernel (CVE-2025-39944). 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:
octeontx2-pf: Fix use-after-free bugs in otx2_sync_tstamp()
The original code relies on cancel_delayed_work() in otx2_ptp_destroy(),
which does not ensure that the delayed work item synctstamp_work has fully
completed if it was already running. This leads to use-after-free scenarios
where otx2_ptp is deallocated by otx2_ptp_destroy(), while synctstamp_work
remains active and attempts to dereference otx2_ptp in otx2_sync_tstamp().
Furthermore, the synctstamp_work is cyclic, the likelihood of triggering
the bug is nonnegligible.
A typical race condition is illustrated below:
CPU 0 (cleanup) | CPU 1 (delayed work callback)
otx2_remove() |
otx2_ptp_destroy() | otx2_sync_tstamp()
cancel_delayed_work() |
kfree(ptp) |
| ptp = container_of(...); //UAF
| ptp-> //UAF
This is confirmed by a KASAN report:
BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x7d7/0x8c0
Write of size 8 at addr ffff88800aa09a18 by task bash/136
...
Call Trace:
dump_stack_lvl+0x55/0x70
print_report+0xcf/0x610
? __run_timer_base.part.0+0x7d7/0x8c0
kasan_report+0xb8/0xf0
? __run_timer_base.part.0+0x7d7/0x8c0
__run_timer_base.part.0+0x7d7/0x8c0
? __pfx___run_timer_base.part.0+0x10/0x10
? __pfx_read_tsc+0x10/0x10
? ktime_get+0x60/0x140
? lapic_next_event+0x11/0x20
? clockevents_program_event+0x1d4/0x2a0
run_timer_sof…
Source: NIST National Vulnerability Database NVD
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-2025-39944 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-2025-39944" on the vendor's site.
CVE-2025-39944 (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-2025-39944 linux-lts Fixed in: 6.1.155-r0
- Debian DEBIAN-CVE-2025-39944 linux Fixed in: 6.1.158-1
- Ubuntu UBUNTU-CVE-2025-39944 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org