What’s Vulnerable › Vulnerabilities

CVE-2026-56101: OpenBSD ieee80211_crypto_tkip.c TKIP MIC Countermeasure Logic Inversion DoS

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-08 · updated 2026-10-27
• Weakness: CWE-697

Description

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.

References

• https://github.com/openbsd/src/commit/1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a
• https://pop.argus-systems.ai/advisory/adv-209.html
• https://www.vulncheck.com/advisories/openbsd-ieee80211-crypto-tkip-c-tkip-mic-countermeasure-logic-inversion-dos

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