Linux: Use After Free
CVE-2025-21715 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 db79e982c5f9e39ab710cbce55b05f2f5e6f1ca9, a53cb72043443ac787ec0b5fa17bb3f8ff3d462b, 7d7d201eb3b766abe590ac0dda7a508b7db3e357 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 0.24% 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 db79e982c5f9e39ab710cbce55b05f2f5e6f1ca9 or a53cb72043443ac787ec0b5fa17bb3f8ff3d462b or 7d7d201eb3b766abe590ac0dda7a508b7db3e357 or c94ab07edc2843e2f3d46dbd82e5c681503aaadf, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.5 or 4.10 or 4.15 or 4.20, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | d28e783c20033b90a64d4e1307bafb56085d8184 up to, but not including, db79e982c5f9e39ab710cbce55b05f2f5e6f1ca9; 4fd0654b8f2129b68203974ddee15f804ec011c2 up to, but not including, a53cb72043443ac787ec0b5fa17bb3f8ff3d462b; cf9e60aa69ae6c40d3e3e4c94dd6c8de31674e9b up to, but not including, 7d7d201eb3b766abe590ac0dda7a508b7db3e357; cf9e60aa69ae6c40d3e3e4c94dd6c8de31674e9b up to, but not including, c94ab07edc2843e2f3d46dbd82e5c681503aaadf; cf9e60aa69ae6c40d3e3e4c94dd6c8de31674e9b up to, but not including, c411f9a5fdc9158e8f7c57eac961d3df3eb4d8ca; cf9e60aa69ae6c40d3e3e4c94dd6c8de31674e9b up to, but not including, 5a54367a7c2378c65aaa4d3cfd952f26adef7aa7; cf9e60aa69ae6c40d3e3e4c94dd6c8de31674e9b up to, but not including, 2013c95df6752d9c88221d0f0f37b6f197969390; cf9e60aa69ae6c40d3e3e4c94dd6c8de31674e9b up to, but not including, 19e65c45a1507a1a2926649d2db3583ed9d55fd9; and 13 more ranges | db79e982c5f9e39ab710cbce55b05f2f5e6f1ca9, a53cb72043443ac787ec0b5fa17bb3f8ff3d462b, 7d7d201eb3b766abe590ac0dda7a508b7db3e357, c94ab07edc2843e2f3d46dbd82e5c681503aaadf, c411f9a5fdc9158e8f7c57eac961d3df3eb4d8ca, 5a54367a7c2378c65aaa4d3cfd952f26adef7aa7 |
| Linux | Linux Kernel | 4.4.262 up to, but not including, 4.5; 4.9.262 up to, but not including, 4.10; 4.14.226 up to, but not including, 4.15; 4.19.181 up to, but not including, 4.20; 5.4.106 up to, but not including, 5.4.291; 5.10.24 up to, but not including, 5.10.235; 5.11.7 up to, but not including, 5.15.179; 5.16 up to, but not including, 6.1.129; and 3 more ranges | 4.5, 4.10, 4.15, 4.20, 5.4.291, 5.10.235 |
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 CISA (ADP).
Official description
In the Linux kernel, the following vulnerability has been resolved: net: davicom: fix UAF in dm9000_drv_remove dm is netdev private data and it cannot be used after free_netdev() call. Using dm after free_netdev() can cause UAF bug. Fix it by moving free_netdev() at the end of the function. This is similar to the issue fixed in commit ad297cd2db89 ("net: qcom/emac: fix UAF in emac_remove"). This bug is detected by our static analysis tool.
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/19e65c45a1507a1a2926649d2db3583ed9d55fd9
- git.kernel.org/stable/c/2013c95df6752d9c88221d0f0f37b6f197969390
- git.kernel.org/stable/c/5a54367a7c2378c65aaa4d3cfd952f26adef7aa7
- git.kernel.org/stable/c/7d7d201eb3b766abe590ac0dda7a508b7db3e357
- git.kernel.org/stable/c/a53cb72043443ac787ec0b5fa17bb3f8ff3d462b
- git.kernel.org/stable/c/c411f9a5fdc9158e8f7c57eac961d3df3eb4d8ca
- git.kernel.org/stable/c/c94ab07edc2843e2f3d46dbd82e5c681503aaadf
- git.kernel.org/stable/c/db79e982c5f9e39ab710cbce55b05f2f5e6f1ca9
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
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