Inverted Comparison Vulnerability in OpenBSD's TKIP Implementation

CVE-2026-56101

What is CVE-2026-56101?

OpenBSD prior to a specific commit includes an inverted comparison flaw in the ieee80211_michael_mic_failure() function. This vulnerability allows unauthenticated attackers within RF range to execute a denial of service attack. By sending two specially crafted TKIP frames, spaced appropriately, an attacker can deauthenticate all associated TKIP stations, which effectively prevents them from re-establishing a connection for up to 90 seconds. The issue arises due to the improper handling of TKIP MIC failure countermeasure checks, where valid signal failures go unnoticed, allowing for potential key recovery exploits without triggering necessary defense mechanisms.

References