CVE-2026-31773CWE-287

CVE-2026-31773

High · published May 1, 2026

CVSS v3.1
8.8
EPSS
0%
Percentile
19.2
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.8 · HIGH
Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00278 · 19.2th percentile
Weakness
CWE-287 · Improper Authentication
Published
2026-05-01T19:16Z
Affected products (15)
ProductVersionsFixed in
linux/linux_kernel≥ 3.15.5, < 3.163.16
linux/linux_kernel≥ 3.16.1, < 5.10.2535.10.253
linux/linux_kernel≥ 5.11, < 5.15.2035.15.203
linux/linux_kernel≥ 5.16, < 6.1.1686.1.168
linux/linux_kernel≥ 6.2, < 6.6.1346.6.134
linux/linux_kernel≥ 6.7, < 6.12.816.12.81
linux/linux_kernel≥ 6.13, < 6.18.226.18.22
linux/linux_kernel≥ 6.19, < 6.19.126.19.12
linux/linux_kernelall versions—
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References (8)
EPSS history
Timeline
  • 01 MAY 14:15Z
    Bluetooth: SMP: derive legacy responder STK authentication from MITM state
    cvelistv5