CVE-2026-56101

Medium

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.

SeverityMedium

CVSS5.3

Exploit probability—

ProductOpenBSD

PublishedSep 8, 2026

First seenSep 8, 2026

Weakness typeCWE-697CWE-697

How to fix

Update

OpenBSD OpenBSD1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a or later

Patches

github.com/openbsd/src/commit/1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a

Affected products

Product	Affected versions	Fixed in
OpenBSD OpenBSD	v < 1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a	1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a

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