Linux: Use After Free
CVE-2026-23272 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 25841e8d4241c6c3763e70ae95050f8108707b46, 022effa9c54903858e443b1225370e6c758d03f6, 25fcaef7948912652905e96922f36583a84fffed 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 0.18% 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 25841e8d4241c6c3763e70ae95050f8108707b46 or 022effa9c54903858e443b1225370e6c758d03f6 or 25fcaef7948912652905e96922f36583a84fffed or e3ccb11fc8249759d23326038c8db987ddaabc77, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.10 or 6.18.17 or 6.19.7, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, 25841e8d4241c6c3763e70ae95050f8108707b46; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, 022effa9c54903858e443b1225370e6c758d03f6; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, 25fcaef7948912652905e96922f36583a84fffed; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, e3ccb11fc8249759d23326038c8db987ddaabc77; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, 86bc4b1a0f672d47ac19f9022432cb6a2e01cb33; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, 6826131c7674329335ca25df2550163eb8a1fd0c; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, ccb8c8f3c1127cf34d18c737309897c68046bf21; 35d0ac9070ef619e3bf44324375878a1c540387b up to, but not including, def602e498a4f951da95c95b1b8ce8ae68aa733a; and 3 more ranges | 25841e8d4241c6c3763e70ae95050f8108707b46, 022effa9c54903858e443b1225370e6c758d03f6, 25fcaef7948912652905e96922f36583a84fffed, e3ccb11fc8249759d23326038c8db987ddaabc77, 86bc4b1a0f672d47ac19f9022432cb6a2e01cb33, 6826131c7674329335ca25df2550163eb8a1fd0c |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Linux | Linux Kernel | 4.9.33 up to, but not including, 4.10; 4.10.1 up to, but not including, 6.18.17; 6.19 up to, but not including, 6.19.7; 4.10; 7.0 | 4.10, 6.18.17, 6.19.7 |
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: nf_tables: unconditionally bump set->nelems before insertion In case that the set is full, a new element gets published then removed without waiting for the RCU grace period, while RCU reader can be walking over it already. To address this issue, add the element transaction even if set is full, but toggle the set_full flag to report -ENFILE so the abort path safely unwinds the set to its previous state. As for element updates, decrement set->nelems to restore it. A simpler fix is to call synchronize_rcu() in the error path. However, with a large batch adding elements to already maxed-out set, this could cause noticeable slowdown of such batches.
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
Other references
- git.kernel.org/stable/c/022effa9c54903858e443b1225370e6c758d03f6
- git.kernel.org/stable/c/25841e8d4241c6c3763e70ae95050f8108707b46
- git.kernel.org/stable/c/25fcaef7948912652905e96922f36583a84fffed
- git.kernel.org/stable/c/86bc4b1a0f672d47ac19f9022432cb6a2e01cb33
- git.kernel.org/stable/c/e3ccb11fc8249759d23326038c8db987ddaabc77
- cert-portal.siemens.com/productcert/html/ssa-784472.html
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.1 High severity
- 8.8 High severity
- 8.8 High severity
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