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Vulnerability record · CVE-2026-21881 · published 8 January 2026

CVE-2026-21881: Kanboard improper authentication vulnerability

Kanboard · Kanboard

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.

9.1 CVSS 3.1 Critical EPSS 0.49% · top 60.1% CWE-287 · Improper authentication
9.1CVSS 3.1 base score
0.49%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc Patch
https://github.com/kanboard/kanboard/releases/tag/v1.2.49 Release Notes
https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w ExploitVendor Advisory
https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-21881), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.