CVE-2025-40920Network attack vector

Digest authentication weakening via predictable nonce generation

Published Aug 11, 2025 · Updated Jan 17, 2026

Predictable nonce generation in Catalyst::Authentication::Credential::HTTP 1.018 and earlier allows remote attackers to weaken Digest authentication. Its nonce constructor assigns nonce and opaque values from Data::UUID create_b64 output, whose version 3 UUIDs derive from known input rather than a cryptographically strong random source. Digest authentication must be enabled and handled by the module; predictable challenges weaken replay protection for protected resources.

CVSS severity8.6
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable nonce generation in Catalyst::Authentication::Credential::HTTP 1.018 and earlier allows remote attackers to weaken Digest authentication. Its nonce constructor assigns nonce and opaque values from Data::UUID create_b64 output, whose version 3 UUIDs derive from known input rather than a cryptographically strong random source. Digest authentication must be enabled and handled by the module; predictable challenges weaken replay protection for protected resources.

The record

CVE
CVE-2025-40920
Published
Aug 11, 2025
Updated
Jan 17, 2026
Vendor
Catalyst
Product
Catalyst::Authentication::Credential::HTTP
Classifications
CWE-340, CWE-338
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Jan 17, 2026Record 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.

  1. Affected versionversion=0.06 <=1.018

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Catalyst · Catalyst::Authentication::Credential::HTTPversion=0.06 <=1.018

Published CVSS scores

8.6CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

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.

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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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