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.
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Advisories
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Fixes
Solution
This issue is fixed starting with version 1.25.2
Workaround
No workaround given by the vendor.
References
History
Wed, 22 Jul 2026 20:30:00 +0000
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Wed, 22 Jul 2026 13:30:00 +0000
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| 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. | |
| Title | 'response-ip'/'rpz' can rewrite BOGUS answers instead of returning SERVFAIL | |
| Weaknesses | CWE-348 | |
| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: NLnet Labs
Published:
Updated: 2026-07-22T18:58:00.043Z
Reserved: 2026-06-22T12:27:22.796Z
Link: CVE-2026-50243
Updated: 2026-07-22T18:57:56.162Z
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OpenCVE Enrichment
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Weaknesses