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Fencer Intel
medium 5.3

CVE-2026-56101 json

OpenBSD ieee80211_crypto_tkip.c TKIP MIC Countermeasure Logic Inversion DoS

published 2mo ago modified 15d ago also EUVD-2026-72935

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

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.

Patch / fix

Is CVE-2026-56101 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • pop.argus-systems.ai https://pop.argus-systems.ai/advisory/adv-209.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.0 CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 5.3 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 6.0 CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • OpenBSD OpenBSD

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.