Authentication weakening via predictable client nonce generation
Published Jul 16, 2025 · Updated Jul 16, 2025
Predictable nonce generation in Authen::DigestMD5 0.01 through 0.04 allows remote attackers to weaken DIGEST-MD5 authentication. DigestMD5.pm hashes the process ID, epoch time, and Perl's noncryptographic rand output to create the client nonce instead of drawing sufficient entropy. Exploitation requires a network authentication exchange and prediction of the small PID space, timestamp, and pseudorandom output, enabling chosen-plaintext attacks and undermining mutual authentication.
Summary
What happened
Predictable nonce generation in Authen::DigestMD5 0.01 through 0.04 allows remote attackers to weaken DIGEST-MD5 authentication. DigestMD5.pm hashes the process ID, epoch time, and Perl's noncryptographic rand output to create the client nonce instead of drawing sufficient entropy. Exploitation requires a network authentication exchange and prediction of the small PID space, timestamp, and pseudorandom output, enabling chosen-plaintext attacks and undermining mutual authentication.
The record
- CVE
- CVE-2025-40919
- Published
- Jul 16, 2025
- Updated
- Jul 16, 2025
- Vendor
- Salvador Fandiño García
- Product
- Authen::DigestMD5
- Classifications
- CWE-340, CWE-338
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 16, 2025CVE publishedPublication date reported by the CVE source.
- Jul 16, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.01 <=0.04
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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