{"id":"CVE-2026-21881","aliases":["DEBIAN-CVE-2026-21881","EUVD-2026-1668","GHSA-wwpf-3j4p-739w"],"status":"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.","severity":{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00486,"percentile":0.42393,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-287"],"published":"2026-01-08T01:08:01Z","modified":"2026-10-28T02:30:47Z","products":[{"vendor":"kanboard","product":"kanboard"}],"references":[{"url":"https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory"]},{"url":"https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc","tags":["x_refsource_MISC","Patch","fix"]},{"url":"https://github.com/kanboard/kanboard/releases/tag/v1.2.49","tags":["x_refsource_MISC","Release Notes","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21881.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21881","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-21881","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-21881","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.","status":"published","published":"2026-01-08T01:08:01.853Z","modified":"2026-01-08T17:13:05.216Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"cna"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T13:41:42.05254Z"}],"euvd":[{"id":"EUVD-2026-1668","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.","status":"published","published":"2026-01-08T01:08:01Z","modified":"2026-01-08T17:13:05Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T19:48:54.487856Z"}],"nvd":[{"id":"CVE-2026-21881","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.","status":"published","published":"2026-01-08T02:15:53.803Z","modified":"2026-06-17T10:19:04.96Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"secondary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:12:03.683495Z"}],"osv":[{"id":"CVE-2026-21881","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.","status":"published","published":"2026-01-08T01:08:01.853Z","modified":"2026-10-28T02:30:47.61765167Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:44:58.42038Z"},{"id":"DEBIAN-CVE-2026-21881","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.","status":"withdrawn","published":"2026-01-08T02:15:53.803Z","modified":"2026-05-07T20:01:46.846562Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T15:45:53.097669Z"}]}}