CVE-2026-23272: Linux kernel · netfilter: nf_tables: unconditionally bump set->nelems before insertion
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 4.15.0-253.265 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.15.0-253.265, 4.15.0-1194.207, 4.15.0-1204.219 +80
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 20 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
Upgrade to a fixed release listed under Affected software.
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 Ubuntu in updated Linux kernel packages. Users should apply the updates corresponding to their distribution and kernel version and reboot the system to activate the fixes. Due to an ABI change, all third-party kernel modules must be recompiled and reinstalled after updating. No additional mitigation steps are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's netfilter nf_tables subsystem was resolved. The issue involved unconditionally incrementing the set->nelems counter before insertion, which could lead to a race condition where a new element is published and removed without waiting for the RCU grace period, potentially causing use-after-free scenarios. The fix involves safely handling the insertion when the set is full by toggling a set_full flag and properly unwinding the set state. This vulnerability affects multiple Linux Azure kernel versions prior to specific fixed releases. A patch is available and included in updated Linux kernel packages. Users should update and reboot their systems to apply the fix.
References
- ubuntu.com/security/CVE-2026-23272 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23272 (opens in a new tab)
- git.kernel.org/stable/c/6826131c7674329335ca25df2550163eb8a1fd0c (opens in a new tab)
- git.kernel.org/stable/c/ccb8c8f3c1127cf34d18c737309897c68046bf21 (opens in a new tab)
- git.kernel.org/stable/c/def602e498a4f951da95c95b1b8ce8ae68aa733a (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8491-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8497-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8498-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8508-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8527-1 (opens in a new tab)