VULNERABILITY INTELLIGENCE

CVE-2026-21881

CVSS score9.1 CRITICAL

EPSS probability0.49%

CISA KEVNot currently listed

Published2026-01-08

Last modified2026-06-17

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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.

Weakness classification

security-advisories@github.com: CWE-287

Primary references

security-advisories@github.com — Patch
security-advisories@github.com — Release Notes
security-advisories@github.com — Exploit, Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0 — Exploit, Vendor Advisory