Vulnerability · Published Sep 8, 2026 · Assigned by VulnCheck

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

Medium 5.3

In plain English

A medium-severity security flaw in OpenBSD from OpenBSD. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities).

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.6%top 50.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
OpenBSD	OpenBSD	0 – before 1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a

Weakness: CWE-697 · Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Argus Systems Advisory technical-description, exploit
Patch Commit patch
https://www.vulncheck.com/advisories/openbsd-ieee80211-crypto-tkip-c-tkip-mic-countermeasure-logic-inversion-dos third-party-advisory