{"id":"CVE-2026-21881","state":"PUBLISHED","title":"Kanboard is Vulnerable to Reverse Proxy Authentication Bypass","description":"Kanboard is project management software focused on Kanban methodology. Versions 1.2.48 and below is vulnerable to a critical authentication bypass when REVERSE_PROXY_AUTH is enabled. The application blindly trusts HTTP headers for user authentication without verifying the request originated from a trusted reverse proxy. An attacker can impersonate any user, including administrators, by simply sending a spoofed HTTP header. This issue is fixed in version 1.2.49.","publishedAt":"2026-01-08T01:08:01.853Z","updatedAt":"2026-01-08T17:13:05.216Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["kanboard kanboard"],"affected":[{"vendor":"kanboard","product":"kanboard","versions":[{"version":"< 1.2.49","status":"affected"}]}],"references":["https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w","https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc","https://github.com/kanboard/kanboard/releases/tag/v1.2.49"],"weaknesses":["CWE-287"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/21xxx/CVE-2026-21881.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-21881","state":"PUBLISHED","datePublished":"2026-01-08T01:08:01.853Z","dateUpdated":"2026-01-08T17:13:05.216Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-01-05T17:24:36.928Z"},"containers":{"cna":{"title":"Kanboard is Vulnerable to Reverse Proxy Authentication Bypass","descriptions":[{"lang":"en","value":"Kanboard is project management software focused on Kanban methodology. Versions 1.2.48 and below is vulnerable to a critical authentication bypass when REVERSE_PROXY_AUTH is enabled. The application blindly trusts HTTP headers for user authentication without verifying the request originated from a trusted reverse proxy. An attacker can impersonate any user, including administrators, by simply sending a spoofed HTTP header. This issue is fixed in version 1.2.49."}],"affected":[{"vendor":"kanboard","product":"kanboard","versions":[{"version":"< 1.2.49","status":"affected"}]}],"references":[{"url":"https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w","name":"https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc","name":"https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc","tags":["x_refsource_MISC"]},{"url":"https://github.com/kanboard/kanboard/releases/tag/v1.2.49","name":"https://github.com/kanboard/kanboard/releases/tag/v1.2.49","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-287","lang":"en","description":"CWE-287: Improper Authentication","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-01-08T01:08:01.853Z"},"source":{"advisory":"GHSA-wwpf-3j4p-739w","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-01-08T17:13:01.913386Z","id":"CVE-2026-21881","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-01-08T17:13:05.216Z"}}]}}}