6.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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GHSA-wc6p-4gwj-jcr8

GHSA-wc6p-4gwj-jcr8: Duplicate Advisory: Keylime has a hardcoded attestation challenge nonce that allows replay attacks

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-q8w6-w55c-ccv5. This link is maintained to preserve external references.

Original Description

A flaw was found in Keylime. An attacker with root access on an enrolled monitored machine, where the Keylime agent runs, can exploit a vulnerability in the Keylime verifier. The verifier uses a hardcoded challenge nonce for Trusted Platform Module (TPM) quote attestation instead of a cryptographically random value. This allows the attacker to stockpile valid TPM quotes and replay them to evade detection after compromising the system. This issue affects only the push model deployment.

(GitHub Advisory)

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GHSA-wc6p-4gwj-jcr8

GHSA-wc6p-4gwj-jcr8:

6.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
keylime	pip	>= 7.14.0, <= 7.14.1	7.14.2

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the use of a hardcoded nonce for TPM quote attestations in Keylime's push model. An attacker with root access on a monitored machine could exploit this to perform replay attacks, effectively hiding malicious activity.

The analysis of the patch commit 5e1ac3f4d70e55cd72673ead3dcf88259798c33a reveals the exact location of the vulnerability. The commit is titled "verifier: Fix hardcoded attestation challenge nonce (CVE-2026-6420)".

The file keylime/models/verifier/evidence.py contains the vulnerable code. Specifically, the generate_challenge method within the CertificationParameters class was using a static, hardcoded byte string for the challenge: self.challenge = bytes.fromhex("49beed365aac777dae23564f5ad0ec").

The patch replaces this hardcoded value with a call to Nonce.generate(bit_length), which generates a cryptographically random nonce, thus mitigating the replay attack vector.

The function EvidenceItem.generate_challenge is the caller of the vulnerable function and is also part of the vulnerable code path. During exploitation, both EvidenceItem.generate_challenge and CertificationParameters.generate_challenge would appear in a runtime profile. Therefore, both are identified as vulnerable functions.

Vulnerable functions

CertificationParameters.generate_challenge

keylime/models/verifier/evidence.py

The function used a hardcoded value for the attestation challenge nonce instead of a cryptographically random one. This allows an attacker to record valid TPM quotes and replay them later to hide system compromise.

EvidenceItem.generate_challenge

keylime/models/verifier/evidence.py

This function is the entry point for generating the challenge. It calls the vulnerable `CertificationParameters.generate_challenge` method. The removal of the `unused-argument` disable comment indicates the parameter is now used to generate a random nonce, which was not the case in the vulnerable version.

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WAF Rule

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Reasoning

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