Linux: Use After Free
CVE-2026-53389 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 6ce7ef41743740ce15c2061561b784148b565b3f, e77fbefd1269b5c123e7c651a1ebdce1b87d19a0, 7ddc29a094d96e9b3aa280433c6dc443df9eabf2 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 0.13% 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 6ce7ef41743740ce15c2061561b784148b565b3f or e77fbefd1269b5c123e7c651a1ebdce1b87d19a0 or 7ddc29a094d96e9b3aa280433c6dc443df9eabf2 or 5ba9950bc9078e19b69cca1e56d1553b125c6857, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.95 or 6.18.38 or 7.1.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | d6732b95b6fbbc6d5bb9d2f809e275763640c4a2 up to, but not including, 6ce7ef41743740ce15c2061561b784148b565b3f; d6732b95b6fbbc6d5bb9d2f809e275763640c4a2 up to, but not including, e77fbefd1269b5c123e7c651a1ebdce1b87d19a0; d6732b95b6fbbc6d5bb9d2f809e275763640c4a2 up to, but not including, 7ddc29a094d96e9b3aa280433c6dc443df9eabf2; d6732b95b6fbbc6d5bb9d2f809e275763640c4a2 up to, but not including, 5ba9950bc9078e19b69cca1e56d1553b125c6857; 6.7 | 6ce7ef41743740ce15c2061561b784148b565b3f, e77fbefd1269b5c123e7c651a1ebdce1b87d19a0, 7ddc29a094d96e9b3aa280433c6dc443df9eabf2, 5ba9950bc9078e19b69cca1e56d1553b125c6857 |
| Linux | Linux Kernel | 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 | 6.12.95, 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
- 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: net/tcp-ao: fix use-after-free of key in del_async path In tcp_ao_delete_key(), the del_async path skips the current_key and rnext_key validity checks present in the synchronous path, assuming these pointers are always NULL on LISTEN sockets. However, if a key was added with set_current=1/set_rnext=1 while the socket was in CLOSE state, current_key and rnext_key will be non-NULL after listen() transitions the socket to LISTEN. When such a key is deleted with del_async=1, hlist_del_rcu() and call_rcu() free the key without clearing the dangling pointers. After the RCU grace period, getsockopt(TCP_AO_INFO) dereferences current_key->sndid and rnext_key->rcvid from freed slab memory. Clear current_key and rnext_key in the del_async path when they reference the key being deleted.
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
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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