Linux: Use After Free
CVE-2025-21968 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 06acfdef370ae018dad9592369e2d2fd9a40c09e, 1397715b011bcdc6ad91b17df7acaee301e89db5, 4964dbc4191ab436877a5e3ecd9c67a4e50b7c36 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 0.21% 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 06acfdef370ae018dad9592369e2d2fd9a40c09e or 1397715b011bcdc6ad91b17df7acaee301e89db5 or 4964dbc4191ab436877a5e3ecd9c67a4e50b7c36 or 378b361e2e30e9729f9a7676f7926868d14f4326, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.236 or 5.15.180 or 6.1.132 or 6.6.84, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, 06acfdef370ae018dad9592369e2d2fd9a40c09e; da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, 1397715b011bcdc6ad91b17df7acaee301e89db5; da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, 4964dbc4191ab436877a5e3ecd9c67a4e50b7c36; da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, 378b361e2e30e9729f9a7676f7926868d14f4326; da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, bac7b8b1a3f1a86eeec85835af106cbdc2b9d9f7; da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, 93d701064e56788663d7c5918fbe5e060d5df587; da3fd7ac0bcf372cc57117bdfcd725cca7ef975a up to, but not including, e65e7bea220c3ce8c4c793b4ba35557f4994ab2b; 5.5 | 06acfdef370ae018dad9592369e2d2fd9a40c09e, 1397715b011bcdc6ad91b17df7acaee301e89db5, 4964dbc4191ab436877a5e3ecd9c67a4e50b7c36, 378b361e2e30e9729f9a7676f7926868d14f4326, bac7b8b1a3f1a86eeec85835af106cbdc2b9d9f7, 93d701064e56788663d7c5918fbe5e060d5df587 |
| Linux | Linux Kernel | 5.5 up to, but not including, 5.10.236; 5.11 up to, but not including, 5.15.180; 5.16 up to, but not including, 6.1.132; 6.2 up to, but not including, 6.6.84; 6.7 up to, but not including, 6.12.20; 6.13 up to, but not including, 6.13.8; 6.14 | 5.10.236, 5.15.180, 6.1.132, 6.6.84, 6.12.20, 6.13.8 |
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 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix slab-use-after-free on hdcp_work [Why] A slab-use-after-free is reported when HDCP is destroyed but the property_validate_dwork queue is still running. [How] Cancel the delayed work when destroying workqueue. (cherry picked from commit 725a04ba5a95e89c89633d4322430cfbca7ce128)
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/06acfdef370ae018dad9592369e2d2fd9a40c09e
- git.kernel.org/stable/c/1397715b011bcdc6ad91b17df7acaee301e89db5
- git.kernel.org/stable/c/378b361e2e30e9729f9a7676f7926868d14f4326
- git.kernel.org/stable/c/4964dbc4191ab436877a5e3ecd9c67a4e50b7c36
- git.kernel.org/stable/c/93d701064e56788663d7c5918fbe5e060d5df587
- git.kernel.org/stable/c/bac7b8b1a3f1a86eeec85835af106cbdc2b9d9f7
- git.kernel.org/stable/c/e65e7bea220c3ce8c4c793b4ba35557f4994ab2b
Other references
Recent Use After Free vulnerabilities
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