Vulnerability in OpenBSD
CVE-2026-56101
OpenBSD before commit 1ee99df contains an inverted comparison vulnerability in the ieee80211_michael_mic_failure() function within sys/net80211/ieee80211_crypto_tkip.c that allows unauthenticated attackers within RF range to trigger denial of service by sending two malformed TKIP frames separated by more than 60 seconds. Attackers can exploit the reversed TKIP MIC failure countermeasure window check to deauthenticate all associated TKIP stations and block reassociation for up to 90 seconds, while within-window MIC failures that should engage countermeasures are silently discarded, leaving key-recovery attempts undetected.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (48.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/openbsd/src/commit/1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a (patch)
- pop.argus-systems.ai/advisory/adv-209.html (technical-description, exploit)
- www.vulncheck.com/advisories/openbsd-ieee80211-crypto-tkip-c-tkip-mic-counterme… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-56101?
- CVE-2026-56101 is a medium-severity vulnerability in OpenBSD, classified under Incorrect Comparison. CVSS score: 5.3/10. Published 2026-09-08.
- How severe is CVE-2026-56101?
- Medium severity. CVSS v3 base score is 5.3 out of 10.