Linux: Use After Free
CVE-2026-31408 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 37e18bc8c9a70d77bd099e2273f328b3bc7f6d0d, d57384e27d1ebf0047e3f00a6e1181b8be9857a2, b0a7da0e3f7442545f071499beb36374714bb9de 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 0.32% 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 37e18bc8c9a70d77bd099e2273f328b3bc7f6d0d or d57384e27d1ebf0047e3f00a6e1181b8be9857a2 or b0a7da0e3f7442545f071499beb36374714bb9de or 45aaca995e4a7a05b272a58e7ab2fff4f611b8f1, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.203 or 6.1.168 or 6.6.131 or 6.12.80, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 37e18bc8c9a70d77bd099e2273f328b3bc7f6d0d; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, d57384e27d1ebf0047e3f00a6e1181b8be9857a2; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, b0a7da0e3f7442545f071499beb36374714bb9de; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 45aaca995e4a7a05b272a58e7ab2fff4f611b8f1; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 108b81514d8f2535eb16651495cefb2250528db3; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 7197462e90b8ce15caa1ae15d4bc2bb8cd21b11e; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, e76e8f0581ef555eacc11dbb095e602fb30a5361; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 598dbba9919c5e36c54fe1709b557d64120cb94b; and 1 more ranges | 37e18bc8c9a70d77bd099e2273f328b3bc7f6d0d, d57384e27d1ebf0047e3f00a6e1181b8be9857a2, b0a7da0e3f7442545f071499beb36374714bb9de, 45aaca995e4a7a05b272a58e7ab2fff4f611b8f1, 108b81514d8f2535eb16651495cefb2250528db3, 7197462e90b8ce15caa1ae15d4bc2bb8cd21b11e |
| Linux | Linux Kernel | 2.6.12.1 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.131; 6.7 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 2.6.12; 7.0 | 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11 |
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
- AdjacentThe attacker must be on the same local network segment.
- 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:A/AC:L/PR:N/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: Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold sco_recv_frame() reads conn->sk under sco_conn_lock() but immediately releases the lock without holding a reference to the socket. A concurrent close() can free the socket between the lock release and the subsequent sk->sk_state access, resulting in a use-after-free. Other functions in the same file (sco_sock_timeout(), sco_conn_del()) correctly use sco_sock_hold() to safely hold a reference under the lock. Fix by using sco_sock_hold() to take a reference before releasing the lock, and adding sock_put() on all exit paths.
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/108b81514d8f2535eb16651495cefb2250528db3
- git.kernel.org/stable/c/45aaca995e4a7a05b272a58e7ab2fff4f611b8f1
- git.kernel.org/stable/c/598dbba9919c5e36c54fe1709b557d64120cb94b
- git.kernel.org/stable/c/7197462e90b8ce15caa1ae15d4bc2bb8cd21b11e
- git.kernel.org/stable/c/b0a7da0e3f7442545f071499beb36374714bb9de
- git.kernel.org/stable/c/d57384e27d1ebf0047e3f00a6e1181b8be9857a2
- git.kernel.org/stable/c/e76e8f0581ef555eacc11dbb095e602fb30a5361
Other references
Recent Use After Free vulnerabilities
- 8.1 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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