Linux: Use After Free
CVE-2025-37924 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 e34a33d5d7e87399af0a138bb32f6a3e95dd83d2, b447463562238428503cfba1c913261047772f90, e18c616718018dfc440e4a2d2b94e28fe91b1861 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 24.5% chance of exploitation within 30 days, which is in the top 2.09% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update Linux to e34a33d5d7e87399af0a138bb32f6a3e95dd83d2 or b447463562238428503cfba1c913261047772f90 or e18c616718018dfc440e4a2d2b94e28fe91b1861 or 28c756738af44a404a91b77830d017bb0c525890, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.138 or 6.6.90 or 6.12.28 or 6.14.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, e34a33d5d7e87399af0a138bb32f6a3e95dd83d2; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, b447463562238428503cfba1c913261047772f90; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, e18c616718018dfc440e4a2d2b94e28fe91b1861; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, 28c756738af44a404a91b77830d017bb0c525890; 0626e6641f6b467447c81dd7678a69c66f7746cf up to, but not including, e86e9134e1d1c90a960dd57f59ce574d27b9a124; 5.15 | e34a33d5d7e87399af0a138bb32f6a3e95dd83d2, b447463562238428503cfba1c913261047772f90, e18c616718018dfc440e4a2d2b94e28fe91b1861, 28c756738af44a404a91b77830d017bb0c525890, e86e9134e1d1c90a960dd57f59ce574d27b9a124 |
| Linux | Linux Kernel | 5.15 up to, but not including, 6.1.138; 6.2 up to, but not including, 6.6.90; 6.7 up to, but not including, 6.12.28; 6.13 up to, but not including, 6.14.6; 6.15 | 6.1.138, 6.6.90, 6.12.28, 6.14.6 |
| Debian | Debian Linux | 11.0 | Not stated |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in kerberos authentication Setting sess->user = NULL was introduced to fix the dangling pointer created by ksmbd_free_user. However, it is possible another thread could be operating on the session and make use of sess->user after it has been passed to ksmbd_free_user but before sess->user is set to NULL.
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: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/28c756738af44a404a91b77830d017bb0c525890
- git.kernel.org/stable/c/b447463562238428503cfba1c913261047772f90
- git.kernel.org/stable/c/e18c616718018dfc440e4a2d2b94e28fe91b1861
- git.kernel.org/stable/c/e34a33d5d7e87399af0a138bb32f6a3e95dd83d2
- git.kernel.org/stable/c/e86e9134e1d1c90a960dd57f59ce574d27b9a124
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2025/08/msg00010.htmlMailing List, Third Party Advisory
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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