{"id":"CVE-2026-50243","state":"PUBLISHED","title":"'response-ip'/'rpz' can rewrite BOGUS answers instead of returning SERVFAIL","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.","publishedAt":"2026-07-22T13:08:21.443Z","updatedAt":"2026-07-22T18:58:00.043Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","source":"NLnet Labs"},"assigner":"NLnet Labs","products":["NLnet Labs Unbound"],"affected":[{"vendor":"NLnet Labs","product":"Unbound","defaultStatus":"unaffected","versions":[{"version":"1.6.2","status":"affected","lessThan":"1.25.2","versionType":"semver"}]}],"references":["https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50243.txt"],"weaknesses":["CWE-348"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/50xxx/CVE-2026-50243.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-50243","state":"PUBLISHED","datePublished":"2026-07-22T13:08:21.443Z","dateUpdated":"2026-07-22T18:58:00.043Z","assignerShortName":"NLnet Labs","assignerOrgId":"206fc3a0-e175-490b-9eaa-a5738056c9f6","dateReserved":"2026-06-22T12:27:22.796Z"},"containers":{"cna":{"title":"'response-ip'/'rpz' can rewrite BOGUS answers instead of returning SERVFAIL","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"NLnet Labs","product":"Unbound","defaultStatus":"unaffected","versions":[{"version":"1.6.2","status":"affected","lessThan":"1.25.2","versionType":"semver"}]}],"references":[{"url":"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50243.txt","tags":["vendor-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"version":"4.0","baseScore":6.3,"baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-348","lang":"en","description":"CWE-348: Use of Less Trusted Source","type":"CWE"}]}],"providerMetadata":{"shortName":"NLnet Labs","orgId":"206fc3a0-e175-490b-9eaa-a5738056c9f6","dateUpdated":"2026-07-22T13:08:21.443Z"},"datePublic":"2026-07-22T00:00:00.000Z","solutions":[{"lang":"en","value":"This issue is fixed starting with version 1.25.2"}],"timeline":[{"time":"2026-05-09T00:00:00.000Z","lang":"en","value":"Issue reported by Qifan Zhang"},{"time":"2026-06-08T00:00:00.000Z","lang":"en","value":"NLnet Labs shares patch"},{"time":"2026-06-11T00:00:00.000Z","lang":"en","value":"Qifan Zhang verifies patch"},{"time":"2026-07-22T00:00:00.000Z","lang":"en","value":"Fixes released with version 1.25.2"}],"credits":[{"lang":"en","value":"Qifan Zhang (Palo Alto Networks)","type":"finder"}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-22T18:57:49.710450Z","id":"CVE-2026-50243","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-22T18:58:00.043Z"}}]}}}