Linux: Use After Free
CVE-2026-23392 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 29538fb3f412f3ce5ad9f97fe7fd84952dacd3af, ec0f801e5ce0162fc4fea95607c716b264d283fb, d2632de96ccb066e0131ad1494241b9c281c60b8 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 0.17% 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 29538fb3f412f3ce5ad9f97fe7fd84952dacd3af or ec0f801e5ce0162fc4fea95607c716b264d283fb or d2632de96ccb066e0131ad1494241b9c281c60b8 or adee3436ccd29f1e514c028899e400cbc6d84065, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.167 or 6.6.130 or 6.12.78 or 6.18.20, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, 29538fb3f412f3ce5ad9f97fe7fd84952dacd3af; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, ec0f801e5ce0162fc4fea95607c716b264d283fb; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, d2632de96ccb066e0131ad1494241b9c281c60b8; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, adee3436ccd29f1e514c028899e400cbc6d84065; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, 7e3955b282eae20d61c75e499c75eade51c20060; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, c8092edb9a11f20f95ccceeb9422b7dd0df337bd; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, e78a2dcc7cfb87b64a631441ca7681492b347ef6; 3b49e2e94e6ebb8b23d0955d9e898254455734f8 up to, but not including, d73f4b53aaaea4c95f245e491aa5eeb8a21874ce; and 1 more ranges | 29538fb3f412f3ce5ad9f97fe7fd84952dacd3af, ec0f801e5ce0162fc4fea95607c716b264d283fb, d2632de96ccb066e0131ad1494241b9c281c60b8, adee3436ccd29f1e514c028899e400cbc6d84065, 7e3955b282eae20d61c75e499c75eade51c20060, c8092edb9a11f20f95ccceeb9422b7dd0df337bd |
| 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 | 4.16.1 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, 6.12.78; 6.13 up to, but not including, 6.18.20; 6.19 up to, but not including, 6.19.10; 4.16; 7.0 | 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 |
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: release flowtable after rcu grace period on error Call synchronize_rcu() after unregistering the hooks from error path, since a hook that already refers to this flowtable can be already registered, exposing this flowtable to packet path and nfnetlink_hook control plane. This error path is rare, it should only happen by reaching the maximum number hooks or by failing to set up to hardware offload, just call synchronize_rcu(). There is a check for already used device hooks by different flowtable that could result in EEXIST at this late stage. The hook parser can be updated to perform this check earlier to this error path really becomes rarely exercised. Uncovered by KASAN reported as use-after-free from nfnetlink_hook path when dumping hooks.
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/7e3955b282eae20d61c75e499c75eade51c20060
- git.kernel.org/stable/c/adee3436ccd29f1e514c028899e400cbc6d84065
- git.kernel.org/stable/c/c8092edb9a11f20f95ccceeb9422b7dd0df337bd
- git.kernel.org/stable/c/d2632de96ccb066e0131ad1494241b9c281c60b8
- git.kernel.org/stable/c/d73f4b53aaaea4c95f245e491aa5eeb8a21874ce
- git.kernel.org/stable/c/e78a2dcc7cfb87b64a631441ca7681492b347ef6
Other references
- git.kernel.org/stable/c/29538fb3f412f3ce5ad9f97fe7fd84952dacd3af
- git.kernel.org/stable/c/ec0f801e5ce0162fc4fea95607c716b264d283fb
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-082556.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
- cert-portal.siemens.com/productcert/html/ssa-784472.html
Recent Use After Free vulnerabilities
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- 7.8 High severity
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