8.8

CVE-2026-31773: linux Improper Authentication

CVSS: 8.8v3.1HighModified
AliasesUBUNTU-CVE-2026-31773DEBIAN-CVE-2026-31773
Published 01-05-2026Last modified 19-10-2026
Open JSON

Vulnerability summary

CVE-2026-31773 is a high (CVSS 8.8) Improper Authentication vulnerability in linux. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.1% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.28%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 42 · Related 40
MGASA-2026-0108MGASA-2026-0110OPENSUSE-SU-2026:21555-1SUSE-SU-2026:23066-1SUSE-SU-2026:23068-1SUSE-SU-2026:23193-1

Timeline

  1. 01-05-2026
    PublishedVulnerability first disclosed.
  2. 19-10-2026
    Last modifiedVulnerability information updated.

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 metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.28%

Chance of exploitation in the next 30 days

Percentile

19%

Versus all other CVEs

30-day change

0.00 pp

From 0.28% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.28%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu157 products
  • linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-136.136
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1061.64
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 9a38659a3d06080715691bd3139f9c4b61f688e3 | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 667f44f1392df6482483756458c48670e579e9ff | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 929db734d12db41ca5f95424db4612397f1bd4a7 | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < b1c6a8e554a39b222c0879a288ea98e338fc4d77 | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 0afc846bd80073ffcd2b8040f2b2fafaea3d9f72 | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 061ee71ac6b03c9f8432fe49538c3682bfcf4cf3 | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 9a6d0db176f082685e0b6149700c0baf3ce2aa8b | ≥ fff3490f47810e2d34b91fb9e31103e923b11c2f, < 20756fec2f0108cb88e815941f1ffff88dc286fe | 14ec593d6bb050cf40a4ade2f9ac9ca050e0412c | ≥ 3.15.5, < 3.16 | 3.16
  • linux_kernel≥ 3.15.5, < 3.16 | ≥ 3.16.1, < 5.10.253 | ≥ 5.11, < 5.15.203 | ≥ 5.16, < 6.1.168 | ≥ 6.2, < 6.6.134 | ≥ 6.7, < 6.12.81 | ≥ 6.13, < 6.18.22 | ≥ 6.19, < 6.19.12 | 3.16 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6
Debian1 product
  • linux< 6.1.170-1 | < 6.12.85-1 | < 6.19.12-1

3 vendors · 160 products

References

39 links
Show all 39 references