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Fencer Vulns
medium 6.5

CVE-2025-40918 json

Authen::SASL::Perl::DIGEST_MD5 versions 2.04 through 2.1800 for Perl generates the cnonce insecurely

published 2025-07-16 15 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-21696

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

Authen::SASL::Perl::DIGEST_MD5 versions 2.04 through 2.1800 for Perl generates 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.

Patch / fix

  • libauthen-sasl-perl Debian 14 2.1900-1

debian advisories DEBIAN-CVE-2025-40918

  • perl-Authen-SASL SLES for SAP applications 16.0, SLES 16.0 2.170.0-160000.3.1
  • perl-Crypt-URandom SLES for SAP applications 16.0, SLES 16.0 0.550.0-160000.1.1
  • perl-Crypt-URandom SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +12 more 0.540.0-150000.1.3.1
  • perl-Authen-SASL SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +12 more 2.16-150000.1.6.1
  • perl-Crypt-URandom SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 0.540.0-1.3.1
  • perl-Authen-SASL SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.16-5.3.1

suse advisories SUSE-SU-2026:21145-1SUSE-SU-2025:03088-1SUSE-SU-2025:03087-1

  • perl-Authen-SASL openSUSE Leap 16.0 2.170.0-160000.3.1
  • perl-Crypt-URandom openSUSE Leap 16.0 0.550.0-160000.1.1
  • perl-Authen-SASL openSUSE Tumbleweed 2.180.0-2.1

opensuse advisories openSUSE-SU-2026:20480-1openSUSE-SU-2025:15385-1

  • perl-authen-sasl Alpine 3.24 2.1900

alpine advisories ALPINE-CVE-2025-40918

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2025-40918 updated cvss 5.9

authen-sasl: Authen::SASL::Perl::DIGEST_MD5 insecure cnonce generation

  • Red Hat Enterprise Linux 6 perl-Authen-SASL Red Hat Enterprise Linux 7 perl-Authen-SASL
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 perl-Authen-SASL Red Hat Enterprise Linux 9 perl-Authen-SASL Red Hat Enterprise Linux 10 perl-Authen-SASL
    affected: workaround, no fix available “Fix deferred”

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

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 39% 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

  • EHUELS Authen::SASL::Perl::DIGEST_MD5

Classification

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

References

Sources

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.