Linux: Use After Free
CVE-2026-68399 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 ac855efc6bb216b262b672af68219e5b731f42a4, f6814814b3bdd6ecb6bc1fc53ba4e827e0185f01, 24139461545e44442df9b80deace26b2eb3e103d 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 0.17% 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 ac855efc6bb216b262b672af68219e5b731f42a4 or f6814814b3bdd6ecb6bc1fc53ba4e827e0185f01 or 24139461545e44442df9b80deace26b2eb3e103d or 01f8a354497ba739f81b691b3702bc4c46500a4d, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6ac99e8f23d4b10258406ca0dd7bffca5f31da9d up to, but not including, ac855efc6bb216b262b672af68219e5b731f42a4; 6ac99e8f23d4b10258406ca0dd7bffca5f31da9d up to, but not including, f6814814b3bdd6ecb6bc1fc53ba4e827e0185f01; 6ac99e8f23d4b10258406ca0dd7bffca5f31da9d up to, but not including, 24139461545e44442df9b80deace26b2eb3e103d; 6ac99e8f23d4b10258406ca0dd7bffca5f31da9d up to, but not including, 01f8a354497ba739f81b691b3702bc4c46500a4d; 6ac99e8f23d4b10258406ca0dd7bffca5f31da9d up to, but not including, 14b49b5ab29979552c219a09e569b424fbbf4a6e; 6ac99e8f23d4b10258406ca0dd7bffca5f31da9d up to, but not including, 7cbd0c4cebe4c9f678d15e6b9ba975e1155a107f; 5.2 | ac855efc6bb216b262b672af68219e5b731f42a4, f6814814b3bdd6ecb6bc1fc53ba4e827e0185f01, 24139461545e44442df9b80deace26b2eb3e103d, 01f8a354497ba739f81b691b3702bc4c46500a4d, 14b49b5ab29979552c219a09e569b424fbbf4a6e, 7cbd0c4cebe4c9f678d15e6b9ba975e1155a107f |
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: bpf: Fix UAF in sock clone early bailouts Similar to recent commit 9b51a6155d14 ("bpf,fork: wipe ->bpf_storage before bailouts that access it"), sk_clone() performs an initial shallow copy of the socket field ->sk_bpf_storage via sock_copy() for the cloned socket newsk. If sk_clone() bails out early (e.g. if sk_filter_charge() fails) prior to calling bpf_sk_storage_clone(), newsk->sk_bpf_storage still points to the parent socket's BPF local storage. When newsk is subsequently freed via sk_free(), the deallocation path (__sk_destruct() -> bpf_sk_storage_free()) destroys the parent socket's BPF local storage, leading to a use-after-free (UAF) on the parent socket. Fix this by resetting newsk->sk_bpf_storage to NULL immediately after sock_copy() in sk_clone(), and remove the now redundant initialization from bpf_sk_storage_clone().
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
Other references
- git.kernel.org/stable/c/01f8a354497ba739f81b691b3702bc4c46500a4d
- git.kernel.org/stable/c/14b49b5ab29979552c219a09e569b424fbbf4a6e
- git.kernel.org/stable/c/24139461545e44442df9b80deace26b2eb3e103d
- git.kernel.org/stable/c/7cbd0c4cebe4c9f678d15e6b9ba975e1155a107f
- git.kernel.org/stable/c/ac855efc6bb216b262b672af68219e5b731f42a4
- git.kernel.org/stable/c/f6814814b3bdd6ecb6bc1fc53ba4e827e0185f01
Recent Use After Free vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
Spotted an error? Tell us.