CVE-2026-40622 Affecting unbound package, versions <1.22.0-2+deb13u3


Severity

Recommended
0.0
high
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.14% (4th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-ECHOLATEST-UNBOUND-18234968
  • published23 Jul 2026
  • disclosed20 May 2026

Introduced: 20 May 2026

CVE-2026-40622  (opens in a new tab)

How to fix?

Upgrade Echo:latest unbound to version 1.22.0-2+deb13u3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream unbound package and not the unbound package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1