CVE-2026-31773
Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SMP: derive legacy responder STK authentication from MITM state The legacy responder path in smp_random() currently labels the stored STK as authenticated whenever pending_sec_level is BT_SECURITY_HIGH. That reflects what the local service requested, not what the pairing flow actually achieved. For Just Works/Confirm legacy pairing, SMP_FLAG_MITM_AUTH stays clear and the resulting STK should remain unauthenticated even if the local side requested HIGH security. Use the established MITM state when storing the responder STK so the key metadata matches the pairing result. This also keeps the legacy path aligned with the Secure Connections code, which already treats JUST_WORKS/JUST_CFM as unauthenticated.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Linux kernel Affected 3 releases
| Version | Status | Fixed in |
|---|---|---|
| 7.0 | Affected | — |
| 3.16 | Affected | — |
| — | Affected | 3.16 |
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 6.12.85-1 |
| sid | Fixed | 6.19.12-1 |
| forky | Fixed | 6.19.12-1 |
| bullseye | Fixed | 6.1.170-1~deb11u1 |
| bookworm | Fixed | 6.1.170-1 |
References
- https://git.kernel.org/stable/c/061ee71ac6b03c9f8432fe49538c3682bfcf4cf3
- https://git.kernel.org/stable/c/0afc846bd80073ffcd2b8040f2b2fafaea3d9f72
- https://git.kernel.org/stable/c/20756fec2f0108cb88e815941f1ffff88dc286fe
- https://git.kernel.org/stable/c/667f44f1392df6482483756458c48670e579e9ff
- https://git.kernel.org/stable/c/929db734d12db41ca5f95424db4612397f1bd4a7
- https://git.kernel.org/stable/c/9a38659a3d06080715691bd3139f9c4b61f688e3
- https://git.kernel.org/stable/c/9a6d0db176f082685e0b6149700c0baf3ce2aa8b
- https://git.kernel.org/stable/c/b1c6a8e554a39b222c0879a288ea98e338fc4d77
- https://www.suse.com/security/cve/CVE-2026-31773.html
- https://security-tracker.debian.org/tracker/CVE-2026-31773
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.