CVE-2025-40918Network attack vector

Authentication compromise via predictable DIGEST-MD5 client nonce

Published Jul 16, 2025 · Updated Nov 4, 2025

Predictable cnonce generation in Authen::SASL 2.04 through 2.1800 allows remote attackers to undermine DIGEST-MD5 authentication. Authen::SASL::Perl::DIGEST_MD5 hashes the process ID, epoch time, and Perl rand output instead of obtaining at least 64 bits of cryptographic randomness. Exploitation requires a DIGEST-MD5 exchange and prediction of these low-entropy inputs, weakening chosen-plaintext resistance and mutual authentication.

CVSS severity6.5
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Predictable cnonce generation in Authen::SASL 2.04 through 2.1800 allows remote attackers to undermine DIGEST-MD5 authentication. Authen::SASL::Perl::DIGEST_MD5 hashes the process ID, epoch time, and Perl rand output instead of obtaining at least 64 bits of cryptographic randomness. Exploitation requires a DIGEST-MD5 exchange and prediction of these low-entropy inputs, weakening chosen-plaintext resistance and mutual authentication.

The record

CVE
CVE-2025-40918
Published
Jul 16, 2025
Updated
Nov 4, 2025
Vendor
Erik Huelsmann
Product
Authen::SASL
Classifications
CWE-338, CWE-340
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.04 <=2.1800

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Erik Huelsmann · Authen::SASLversion=2.04 <=2.1800

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo