Linux: Use After Free
CVE-2026-23461 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 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d, c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf, da3000cbe4851458a22be38bb18c0689c39fdd5f 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 0.24% 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 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d or c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf or da3000cbe4851458a22be38bb18c0689c39fdd5f or 71030f3b3015a412133a805ff47970cdcf30c2b8, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.130 or 6.12.78 or 6.14 or 6.18.20, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | efc30877bd4bc85fefe98d80af60fafc86e5775e up to, but not including, 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d; f87271d21dd4ee83857ca11b94e7b4952749bbae up to, but not including, c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf; ab4eedb790cae44313759b50fe47da285e2519d5 up to, but not including, da3000cbe4851458a22be38bb18c0689c39fdd5f; ab4eedb790cae44313759b50fe47da285e2519d5 up to, but not including, 71030f3b3015a412133a805ff47970cdcf30c2b8; ab4eedb790cae44313759b50fe47da285e2519d5 up to, but not including, 752a6c9596dd25efd6978a73ff21f3b592668f4a; 18ab6b6078fa8191ca30a3065d57bf35d5635761; 6.6.84 up to, but not including, 6.6.130; 6.12.20 up to, but not including, 6.12.78; and 2 more ranges | 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d, c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf, da3000cbe4851458a22be38bb18c0689c39fdd5f, 71030f3b3015a412133a805ff47970cdcf30c2b8, 752a6c9596dd25efd6978a73ff21f3b592668f4a, 6.6.130 |
| Linux | Linux Kernel | 6.6.84 up to, but not including, 6.6.130; 6.12.20 up to, but not including, 6.12.78; 6.13.8 up to, but not including, 6.14; 6.14.1 up to, but not including, 6.18.20; 6.19 up to, but not including, 6.19.10; 6.14; 7.0 | 6.6.130, 6.12.78, 6.14, 6.18.20, 6.19.10 |
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: L2CAP: Fix use-after-free in l2cap_unregister_user After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to conn->users. However, l2cap_register_user() and l2cap_unregister_user() don't use conn->lock, creating a race condition where these functions can access conn->users and conn->hchan concurrently with l2cap_conn_del(). This can lead to use-after-free and list corruption bugs, as reported by syzbot. Fix this by changing l2cap_register_user() and l2cap_unregister_user() to use conn->lock instead of hci_dev_lock(), ensuring consistent locking for the l2cap_conn structure.
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/11a87dd5df428a4b79a84d2790cac7f3c73f1f0d
- git.kernel.org/stable/c/71030f3b3015a412133a805ff47970cdcf30c2b8
- git.kernel.org/stable/c/752a6c9596dd25efd6978a73ff21f3b592668f4a
- git.kernel.org/stable/c/c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf
- git.kernel.org/stable/c/da3000cbe4851458a22be38bb18c0689c39fdd5f
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
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