Authen::DigestMD5 versions 0.01 through 0.04 for Perl generate the cnonce insecurely

published 2025-07-16 15 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-21702

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits: 0; none known

Authen::DigestMD5 versions 0.01 through 0.02 for Perl generate the cnonce insecurely.

The cnonce (client nonce) is generated from an MD5 hash of the PID, the epoch time and the built-in rand function. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage.

According to RFC 2831, "The cnonce-value is an opaque quoted string value provided by the client and used by both client and server to avoid chosen plaintext attacks, and to provide mutual authentication. The security of the implementation depends on a good choice. It is RECOMMENDED that it contain at least 64 bits of entropy."

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-40919 updated 2026-06-27 cvss 5.9

authen-digestmd5: Authen::DigestMD5 insecure cnonce generation

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 15 mo ago (2025-07-16)

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected products

SALVA Authen::DigestMD5

Classification

Weakness

CWE-340 Generation of Predictable Numbers or Identifiers
CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

References

Sources

CVE List CVE-2025-40919
NVD CVE-2025-40919

Fencer Vulns 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.

Summary