PT-2026-2118 · Kanboard · Kanboard

Huseynkhanli · Published 2026-01-08 · Updated 2026-04-20 · CVE-2026-21881

Positive Technologies (AI Summary)

CVSS v3.1

9.1

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions Kanboard versions 1.2.48 and below

Description Kanboard is project management software based on the Kanban methodology. When the REVERSE PROXY AUTH setting is enabled, the application does not properly verify the source of HTTP headers used for user authentication, leading to a critical authentication bypass. An attacker can exploit this by sending spoofed HTTP headers to impersonate any user, including administrators. The application blindly trusts these headers without confirming they originate from a trusted reverse proxy.

Recommendations Kanboard versions 1.2.48 and below: Upgrade to version 1.2.49 or later.

Exploit

Fix

Improper Authentication

Weakness Enumeration

CWE-287

Related Identifiers

CVE-2026-21881

GHSA-WWPF-3J4P-739W

Affected Products

Kanboard

References · 15

• 🔥 https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w · Exploit
• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21881.json · Exploit
• https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-21881 · Security Note
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-21881 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-21881 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-21881 · Vendor Advisory
• https://github.com/kanboard/kanboard/releases/tag/v1.2.49 · Note
• https://twitter.com/0dayPublishing/status/2009074052258816403 · Twitter Post
• https://twitter.com/VulmonFeeds/status/2009132037920162178 · Twitter Post
• https://twitter.com/pulsepatchio/status/2009635026011324458 · Twitter Post
• https://twitter.com/SecurityAr58409/status/2046171784488054862 · Twitter Post
• https://t.me/CVEtracker/41671 · Telegram Post
• https://twitter.com/pulsepatchio/status/2009271339769606412 · Twitter Post
• https://twitter.com/CVEnew/status/2009149977910759763 · Twitter Post