CVE WatchJul 22, 2026

CVE-2026-50243

In NLnet Labs Unbound 1.6.2 up to and including 1.25.1, when Unbound is configured with the 'respip' module in front of the validator togeth

CVSS

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No CVSS

EPSS

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KEV

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Exploit Today

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0-100

Published: Jul 22, 2026 · Last modified: Jul 22, 2026 · CWE-348

EPSS · 30d

Not enough EPSS history yet.

Technical description

In NLnet Labs Unbound 1.6.2 up to and including 1.25.1, when Unbound is configured with the 'respip' module in front of the validator together with a 'response-ip' redirect rule or an RPZ file with an RPZ-IP trigger, the rewriting handler does not check the security status of the upstream answer and can instead rewrite a BOGUS A/AAAA answer to point to an operator's configured IP. If the validator finds an expired or otherwise invalid RRSIG on an answer whose A record falls within a 'response-ip'/RPZ configuration, the answer is still rewritten and given a hard coded security level of INSECURE. This results in the client receiving an INSECURE NOERROR reply rewritten by the operator's configured IP. A malicious actor can exploit the possible poisonous effect by spoofing a BOGUS A/AAAA answer that falls inside the operator's configured subnet rewrites. Such DNSSEC protected answers are then insecurely redirected to the operator's configured target.

Official references

www.nlnetlabs.nlhttps://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50243.txt

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