CVE-2026-23319: Linux kernel · bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · patch available : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Mar 2026
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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?arch=source&distro=questingOther 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
A patch is available and has been released by the vendor in official Ubuntu security updates (USN-8567-1 and USN-8574-1). Users should apply the kernel updates and reboot their systems to fully mitigate this vulnerability. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be required after updating. No additional mitigation steps are indicated by the vendor advisory.
Description
A use-after-free (UAF) vulnerability was identified and fixed in the Linux kernel's BPF subsystem, specifically in the function bpf_trampoline_link_cgroup_shim. The flaw occurs due to a race condition where a resource is considered released but still referenced, allowing a potential use-after-free during a deferred cleanup window. The issue was addressed by adding an atomic non-zero reference count check to prevent incrementing the refcount if it is already zero. This vulnerability affects multiple Linux kernel versions prior to 6.8.0-1064.72 and related builds. A patch is available and included in official Ubuntu security updates. The CVSS v3.1 score is 7.8, indicating a high severity impact on confidentiality, integrity, and availability. No known exploits are reported in the wild.
References
- ubuntu.com/security/CVE-2026-23319 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23319 (opens in a new tab)
- git.kernel.org/linus/56145d237385ca0e7ca9ff7b226aaf2eb8ef368b (opens in a new tab)
- git.kernel.org/stable/c/3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2 (opens in a new tab)
- git.kernel.org/stable/c/4e8a0005d633a4adc98e3b65d5080f93b90d356b (opens in a new tab)
- git.kernel.org/stable/c/529e685e522b9d7fb379dbe6929dcdf520e34c8c (opens in a new tab)
- git.kernel.org/stable/c/56145d237385ca0e7ca9ff7b226aaf2eb8ef368b (opens in a new tab)
- git.kernel.org/stable/c/9b02c5c4147f8af8ed783c8deb5df927a55c3951 (opens in a new tab)
- git.kernel.org/stable/c/cfcfa0ca0212162aa472551266038e8fd6768cff (opens in a new tab)
- ubuntu.com/security/notices/USN-8567-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8596-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8606-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8607-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8608-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8609-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-3 (opens in a new tab)