CVE-2026-42955
Extra fix for CVE-2026-40622 to also clamp the TTL of A/AAAA records disallowing a one-time 'ghost domain' delegation renewal via glue records
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Description
In NLnet Labs Unbound 1.16.2 up to and including 1.25.1, a similar vulnerability as with CVE-2026-40622 in the 'ghost domain names' family of attacks was found in Unbound that could extend the ghost domain window by up to one cached TTL configured value for A/AAAA glue records. 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 A/AAAA query can cause Unbound to overwrite the cached expired parent-side glue 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 query is required since Unbound implicitly performs that query. This is a variant of CVE-2026-40622 which only addressed the NS query.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
References (1)
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CVSS
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