CVE-2026-72251: Linux kernel · netfilter: nf_nat_sip: reload possible stale data pointer
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +43
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 15 Aug 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
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther 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 should be applied to affected Linux kernel versions. The vendor advisory confirms that this issue has been fixed. Systems running affected versions should be updated to the patched kernel releases to mitigate this vulnerability.
Description
A vulnerability in the Linux kernel's netfilter nf_nat_sip module could cause stale data pointers to be used after skb_ensure_writable() reallocates a buffer, potentially leading to memory corruption. Additionally, the vulnerability involves improper handling of TCP packets in a UDP-specific function, which could overwrite TCP sequence numbers. This issue has been resolved with a patch that rebuilds pointers after skb cloning and disables the problematic code path for TCP streams.
References
- nvd.nist.gov/vuln/detail/CVE-2026-72251 (opens in a new tab)
- git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7 (opens in a new tab)
- git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27 (opens in a new tab)
- git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2 (opens in a new tab)
- git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68 (opens in a new tab)
- git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532 (opens in a new tab)
- git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c (opens in a new tab)
- git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1 (opens in a new tab)
- git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17 (opens in a new tab)
- ubuntu.com/security/CVE-2026-72251 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-72251 (opens in a new tab)
- git.kernel.org/linus/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8876-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)