Linux: Use After Free
CVE-2026-23351 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 65ca51b9fb85477ab92a04295aed34b38f7c062e, c0f1f85097ac2b6e7d750fe4d05807985cd3fd3a, 16f3595c0441d87dfa005c47d8f95be213afaa9e as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 65ca51b9fb85477ab92a04295aed34b38f7c062e or c0f1f85097ac2b6e7d750fe4d05807985cd3fd3a or 16f3595c0441d87dfa005c47d8f95be213afaa9e or 7864c667aed01a58b87ca518a631322cd0ac34c0, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.167 or 6.6.130, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, 65ca51b9fb85477ab92a04295aed34b38f7c062e; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, c0f1f85097ac2b6e7d750fe4d05807985cd3fd3a; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, 16f3595c0441d87dfa005c47d8f95be213afaa9e; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, 7864c667aed01a58b87ca518a631322cd0ac34c0; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, c12d570d71920903a1a0468b7d13b085203d0c93; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, 500a50a301ce962b019ab95053ac70264fec2c21; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, aff13667708dfa0dce136b8efd81baa9fa6ef261; 3c4287f62044a90e73a561aa05fc46e62da173da up to, but not including, 9df95785d3d8302f7c066050117b04cd3c2048c2; and 1 more ranges | 65ca51b9fb85477ab92a04295aed34b38f7c062e, c0f1f85097ac2b6e7d750fe4d05807985cd3fd3a, 16f3595c0441d87dfa005c47d8f95be213afaa9e, 7864c667aed01a58b87ca518a631322cd0ac34c0, c12d570d71920903a1a0468b7d13b085203d0c93, 500a50a301ce962b019ab95053ac70264fec2c21 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 5.6.1 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.77; 6.13 up to, but not including, 6.18.17; 6.19 up to, but not including, 6.19.7; 5.6; and 1 more ranges | 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.77, 6.18.17 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo: split gc into unlink and reclaim phase Yiming Qian reports Use-after-free in the pipapo set type: Under a large number of expired elements, commit-time GC can run for a very long time in a non-preemptible context, triggering soft lockup warnings and RCU stall reports (local denial of service). We must split GC in an unlink and a reclaim phase. We cannot queue elements for freeing until pointers have been swapped. Expired elements are still exposed to both the packet path and userspace dumpers via the live copy of the data structure. call_rcu() does not protect us: dump operations or element lookups starting after call_rcu has fired can still observe the free'd element, unless the commit phase has made enough progress to swap the clone and live pointers before any new reader has picked up the old version. This a similar approach as done recently for the rbtree backend in commit 35f83a75529a ("netfilter: nft_set_rbtree: don't gc elements on insert").
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/16f3595c0441d87dfa005c47d8f95be213afaa9e
- git.kernel.org/stable/c/500a50a301ce962b019ab95053ac70264fec2c21
- git.kernel.org/stable/c/65ca51b9fb85477ab92a04295aed34b38f7c062e
- git.kernel.org/stable/c/7864c667aed01a58b87ca518a631322cd0ac34c0
- git.kernel.org/stable/c/9df95785d3d8302f7c066050117b04cd3c2048c2
- git.kernel.org/stable/c/aff13667708dfa0dce136b8efd81baa9fa6ef261
- git.kernel.org/stable/c/c0f1f85097ac2b6e7d750fe4d05807985cd3fd3a
- git.kernel.org/stable/c/c12d570d71920903a1a0468b7d13b085203d0c93
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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