CVE-2025-38734: Linux kernel · net/smc: fix UAF on smcsk after smc_listen_out() BPF CI testing report a UAF issue:
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 6.8.0-1046.49~22.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1046.49~22.04.1, 6.8.0-1051.57~22.04.1, 6.8.0-1046.53~22.04.1 +27
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 5 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
An official patch is available and should be applied to affected Linux kernel versions. The vendor advisory confirms the issue is fixed. Users should update their systems to the patched kernel versions to mitigate this vulnerability.
Description
A use-after-free (UAF) vulnerability in the Linux kernel's net/smc subsystem was resolved. The issue occurs after smc_listen_out_connected() when newclcsock->sk may become NULL due to socket closure timing, leading to a kernel NULL pointer dereference. This flaw can cause kernel crashes and potentially allow an attacker to compromise system integrity. The vulnerability affects specific Linux kernel versions and has a high CVSS score of 9.8. An official patch is available from the vendor.
References
- ubuntu.com/security/CVE-2025-38734 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-38734 (opens in a new tab)
- git.kernel.org/linus/d9cef55ed49117bd63695446fb84b4b91815c0b4 (opens in a new tab)
- git.kernel.org/stable/c/070b4af44c4b6e4c35fb1ca7001a6a88fd2d318f (opens in a new tab)
- git.kernel.org/stable/c/2e765ba0ee0eae35688b443e97108308a716773e (opens in a new tab)
- git.kernel.org/stable/c/85545f1525f9fa9bf44fec77ba011024f15da342 (opens in a new tab)
- git.kernel.org/stable/c/d9cef55ed49117bd63695446fb84b4b91815c0b4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8052-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-7 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-8 (opens in a new tab)
- ubuntu.com/security/notices/USN-8052-2 (opens in a new tab)