CVE-2026-31773
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.28% probability · 21th percentile
- CISA KEV
- Not listed
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/061ee71ac6b03c9f8432fe49538c3682bfcf4cf3Patch
- https://git.kernel.org/stable/c/0afc846bd80073ffcd2b8040f2b2fafaea3d9f72Patch
- https://git.kernel.org/stable/c/20756fec2f0108cb88e815941f1ffff88dc286fePatch
- https://git.kernel.org/stable/c/667f44f1392df6482483756458c48670e579e9ffPatch
- https://git.kernel.org/stable/c/929db734d12db41ca5f95424db4612397f1bd4a7Patch
- https://git.kernel.org/stable/c/9a38659a3d06080715691bd3139f9c4b61f688e3Patch
- https://git.kernel.org/stable/c/9a6d0db176f082685e0b6149700c0baf3ce2aa8bPatch
- https://git.kernel.org/stable/c/b1c6a8e554a39b222c0879a288ea98e338fc4d77Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.