CVE-2026-21881

CriticalCVSS 9.1/10Last modified Jun 17, 2026

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.

Metrics

CVSS 3.1 9.1/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weakness enumeration

CWE-287

Affected software

Vendor	Product	Versions
kanboard	kanboard	< 1.2.49

References

https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fcPatch
https://github.com/kanboard/kanboard/releases/tag/v1.2.49Release Notes
https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739wExploit, Vendor Advisory
https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739wExploit, Vendor Advisory

Timeline

Published: Jan 8, 2026
Last modified: Jun 17, 2026
NVD status: Analyzed

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