Linux: Use After Free
CVE-2026-63797 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.4 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. The record lists versions 1306fc4f76f765727a6d5aefbf08ef0c8f32996f, ddf13f91ca82c94ef7ad9c41a434a03313f8eb1b, c5ebb06c7e24d531b68707168e04698859d642bc 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 0.15% 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 1306fc4f76f765727a6d5aefbf08ef0c8f32996f or ddf13f91ca82c94ef7ad9c41a434a03313f8eb1b or c5ebb06c7e24d531b68707168e04698859d642bc or 104d100212396801f1d9d388282f746e23e2bfd6, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.178 or 6.6.144 or 6.12.95 or 6.18.38, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | bc69d10665690492421d926b1cd9a7a36bffd691 up to, but not including, 1306fc4f76f765727a6d5aefbf08ef0c8f32996f; bc69d10665690492421d926b1cd9a7a36bffd691 up to, but not including, ddf13f91ca82c94ef7ad9c41a434a03313f8eb1b; bc69d10665690492421d926b1cd9a7a36bffd691 up to, but not including, c5ebb06c7e24d531b68707168e04698859d642bc; bc69d10665690492421d926b1cd9a7a36bffd691 up to, but not including, 104d100212396801f1d9d388282f746e23e2bfd6; bc69d10665690492421d926b1cd9a7a36bffd691 up to, but not including, ff268cd9ccbce6472a0658791b417bf11c31ee39; bc69d10665690492421d926b1cd9a7a36bffd691 up to, but not including, 1ff3f528e67d20e2b1483dcaba899dc7832b2e6b; 5.18 | 1306fc4f76f765727a6d5aefbf08ef0c8f32996f, ddf13f91ca82c94ef7ad9c41a434a03313f8eb1b, c5ebb06c7e24d531b68707168e04698859d642bc, 104d100212396801f1d9d388282f746e23e2bfd6, ff268cd9ccbce6472a0658791b417bf11c31ee39, 1ff3f528e67d20e2b1483dcaba899dc7832b2e6b |
| Linux | Linux Kernel | 5.18 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.144; 6.7 up to, but not including, 6.12.95; 6.13 up to, but not including, 6.18.38; 6.19 up to, but not including, 7.1.3 | 6.1.178, 6.6.144, 6.12.95, 6.18.38, 7.1.3 |
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
- NoneNo account or login is needed.
- 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:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.4 | High | CNA |
| CVSS 3.1 | 8.4 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: rpmsg: char: Fix use-after-free on probe error path rpmsg_chrdev_probe() stores the newly allocated eptdev in the default endpoint's priv pointer before calling rpmsg_chrdev_eptdev_add(). If rpmsg_chrdev_eptdev_add() then fails, its error path frees eptdev while the default endpoint may still dispatch callbacks with the stale priv pointer. Avoid publishing eptdev through the default endpoint until rpmsg_chrdev_eptdev_add() succeeds. Messages received before the priv pointer is published should be ignored by rpmsg_ept_cb(). Flow-control updates can hit rpmsg_ept_flow_cb() in the same window, so make both callbacks return success when priv is 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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/104d100212396801f1d9d388282f746e23e2bfd6
- git.kernel.org/stable/c/1306fc4f76f765727a6d5aefbf08ef0c8f32996f
- git.kernel.org/stable/c/1ff3f528e67d20e2b1483dcaba899dc7832b2e6b
- git.kernel.org/stable/c/c5ebb06c7e24d531b68707168e04698859d642bc
- git.kernel.org/stable/c/ddf13f91ca82c94ef7ad9c41a434a03313f8eb1b
- git.kernel.org/stable/c/ff268cd9ccbce6472a0658791b417bf11c31ee39
Recent Use After Free vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
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