{"id":"CVE-2026-75514","state":"PUBLISHED","title":"BunkerWeb: rDNS bypass via missing forward-confirmation (FCrDNS) in blacklist, greylist, and antibot","description":"BunkerWeb is an open-source, next-generation Web Application Firewall. Prior to 1.6.13, the blacklist, greylist, and antibot modules in src/common/core/blacklist/blacklist.lua, src/common/core/greylist/greylist.lua, and src/common/core/antibot/antibot.lua trust PTR suffix matches in IGNORE_RDNS, GREYLIST_RDNS, and ANTIBOT_IGNORE_RDNS without using get_ips to confirm that the hostname resolves to the client address. An unauthenticated remote attacker who controls a PTR record can spoof a trusted suffix to bypass rDNS-based blacklisting, gain greylist treatment, or skip an antibot challenge. This issue is fixed in version 1.6.13.","publishedAt":"2026-08-20T18:31:51.527Z","updatedAt":"2026-08-20T19:00:33.894Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["bunkerity bunkerweb"],"affected":[{"vendor":"bunkerity","product":"bunkerweb","versions":[{"version":"< 1.6.13","status":"affected"}]}],"references":["https://github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm","https://github.com/bunkerity/bunkerweb/pull/3710","https://github.com/bunkerity/bunkerweb/commit/1a97e5b3f977130a1b84507a9e1f703c8eec12eb","https://github.com/bunkerity/bunkerweb/releases/tag/v1.6.13"],"weaknesses":["CWE-350"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/75xxx/CVE-2026-75514.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-75514","state":"PUBLISHED","datePublished":"2026-08-20T18:31:51.527Z","dateUpdated":"2026-08-20T19:00:33.894Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-17T20:49:21.599Z"},"containers":{"cna":{"title":"BunkerWeb: rDNS bypass via missing forward-confirmation (FCrDNS) in blacklist, greylist, and antibot","descriptions":[{"lang":"en","value":"BunkerWeb is an open-source, next-generation Web Application Firewall. Prior to 1.6.13, the blacklist, greylist, and antibot modules in src/common/core/blacklist/blacklist.lua, src/common/core/greylist/greylist.lua, and src/common/core/antibot/antibot.lua trust PTR suffix matches in IGNORE_RDNS, GREYLIST_RDNS, and ANTIBOT_IGNORE_RDNS without using get_ips to confirm that the hostname resolves to the client address. An unauthenticated remote attacker who controls a PTR record can spoof a trusted suffix to bypass rDNS-based blacklisting, gain greylist treatment, or skip an antibot challenge. This issue is fixed in version 1.6.13."}],"affected":[{"vendor":"bunkerity","product":"bunkerweb","versions":[{"version":"< 1.6.13","status":"affected"}]}],"references":[{"url":"https://github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm","name":"https://github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/bunkerity/bunkerweb/pull/3710","name":"https://github.com/bunkerity/bunkerweb/pull/3710","tags":["x_refsource_MISC"]},{"url":"https://github.com/bunkerity/bunkerweb/commit/1a97e5b3f977130a1b84507a9e1f703c8eec12eb","name":"https://github.com/bunkerity/bunkerweb/commit/1a97e5b3f977130a1b84507a9e1f703c8eec12eb","tags":["x_refsource_MISC"]},{"url":"https://github.com/bunkerity/bunkerweb/releases/tag/v1.6.13","name":"https://github.com/bunkerity/bunkerweb/releases/tag/v1.6.13","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-350","lang":"en","description":"CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-20T18:31:51.527Z"},"source":{"advisory":"GHSA-q54j-5484-pvjm","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-20T18:58:07.780705Z","id":"CVE-2026-75514","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":"2026-08-20T19:00:33.894Z"}}]}}}