Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user

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Summary

CVECVE-2026-23461
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-03 16:16:33 UTC
Updated2026-05-20 15:30:09 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000240000 probability, percentile 0.064960000 (date 2026-04-27)

Problem Types: CWE-416

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.8HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected efc30877bd4bc85fefe98d80af60fafc86e5775e 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d git Not specified
CNA Linux Linux affected f87271d21dd4ee83857ca11b94e7b4952749bbae c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf git Not specified
CNA Linux Linux affected ab4eedb790cae44313759b50fe47da285e2519d5 da3000cbe4851458a22be38bb18c0689c39fdd5f git Not specified
CNA Linux Linux affected ab4eedb790cae44313759b50fe47da285e2519d5 71030f3b3015a412133a805ff47970cdcf30c2b8 git Not specified
CNA Linux Linux affected ab4eedb790cae44313759b50fe47da285e2519d5 752a6c9596dd25efd6978a73ff21f3b592668f4a git Not specified
CNA Linux Linux affected 18ab6b6078fa8191ca30a3065d57bf35d5635761 git Not specified
CNA Linux Linux affected 6.14 Not specified
CNA Linux Linux unaffected 6.14 semver Not specified
CNA Linux Linux unaffected 6.6.130 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.78 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.20 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.10 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/71030f3b3015a412133a805ff47970cdcf30c2b8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/752a6c9596dd25efd6978a73ff21f3b592668f4a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/11a87dd5df428a4b79a84d2790cac7f3c73f1f0d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/da3000cbe4851458a22be38bb18c0689c39fdd5f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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