CVE-2026-6420

Attestation bypass via hardcoded TPM quote nonce

Published May 6, 2026 · Updated May 6, 2026

Authentication bypass in Keylime 7.14.0 through 7.14.1 allows local users with root access to evade TPM quote attestation. CertificationParameters.generate_challenge() in the push protocol replaces random nonce generation with a fixed byte string, allowing precomputed valid quotes to be replayed. Exploitation requires root on an enrolled monitored node and affects only push-mode deployments, temporarily hiding post-quote compromise from that node's verifier.

CVSS severity6.3
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Keylime 7.14.0 through 7.14.1 allows local users with root access to evade TPM quote attestation. CertificationParameters.generate_challenge() in the push protocol replaces random nonce generation with a fixed byte string, allowing precomputed valid quotes to be replayed. Exploitation requires root on an enrolled monitored node and affects only push-mode deployments, temporarily hiding post-quote compromise from that node's verifier.

The record

CVE
CVE-2026-6420
Published
May 6, 2026
Updated
May 6, 2026
Vendor
389 Directory Server
Product
Red Hat Enterprise Linux 10
Classifications
CWE-547, CWE-1241, CWE-329, CWE-294, T1562.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

6.3Red HatCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-547Use of Hard-coded, Security-relevant Constants
CWE-1241Use of Predictable Algorithm in Random Number Generator
CWE-329Generation of Predictable IV with CBC Mode
CWE-294Authentication Bypass by Capture-replay
T1562.001Impair Defenses: Disable or Modify Tools

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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