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NVD / CVE Program· CNA VulnCheck

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

Noroxi assessment

Priority: Monitor (action score 24/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.60% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: OpenBSD OpenBSD 1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a.

Low priority for now. Upgrade to OpenBSD OpenBSD 1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5a or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 6.0 · v4.0—No exploit Fix available
Published
Sep 8, 2026
Updated
Oct 27, 2026
EPSS
0.6% · 49th percentile

Report tools

JSON

Action score

24

Monitor

Low priority for now.

CVSS
24 / 40 · 6.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
6.0
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-56101

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • OpenBSD OpenBSD

    • before 1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5aaffected · git

Same product

openbsd: all records

Other highest-scoring records for the same primary product.

  • CVE-2007-5365Stack-based buffer overflow in the cons_options function in options.c in dhcpd in OpenBSD 4.0 through 4.2, and some other dhcpd implementati
    52Plan
  • CVE-2007-1365Buffer overflow in kern/uipc_mbuf2.c in OpenBSD 3.9 and 4.0 allows remote attackers to execute arbitrary code via fragmented IPv6 packets du
    46Plan
  • CVE-2004-0220isakmpd in OpenBSD 3.4 and earlier allows remote attackers to cause a denial of service via an ISAKMP packet with a malformed Cert Request p
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-56099Jun 18, 2026 · OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input
    27Monitor
  • ← EarlierCVE-2026-57589Jun 24, 2026 · sys/kern/sysv_sem.c in OpenBSD through 7.9 has a use-after-free allowing local privilege escalation to root.
    31Monitor
  • Later →CVE-2026-103547Sep 30, 2026 · In ldapd in OpenBSD 7.8 before errata 057 and 7.9 before errata 021, delegated BSD authentication results are correlated only by the LDAP ch
    36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
OpenBSD OpenBSD1ee99dfcc4ddc87afc6395d5d3094e9d2314fb5aVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-697 · Incorrect Comparison

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

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References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records