CVE-2026-40622 (High) detected in src4.0.4

[mend-bolt-for-github]

CVE-2026-40622 - High Severity Vulnerability

Vulnerable Library - src4.0.4

Library home page: https://github.com/MidnightBSD/src.git

Found in base branches: stable/4.0, master

Vulnerable Source Files (1)

/contrib/unbound/services/cache/rrset.c

Vulnerability Details

NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.

Publish Date: 2026-05-20

URL: CVE-2026-40622

CVSS 3 Score Details (7.5)

Base Score Metrics:

• Exploitability Metrics:
  • Attack Vector: Network
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: None
  • Scope: Unchanged
• Impact Metrics:
  • Confidentiality Impact: None
  • Integrity Impact: High
  • Availability Impact: None

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Release Date: 2026-05-20

Fix Resolution: https://github.com/NLnetLabs/unbound.git - release-1.25.1

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