CVE-2026-21881

Name: CVE-2026-21881
Creator: NVD / NIST
Published: 2026-01-08T02:15:53.803+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.1/10EPSS 0.43%

Last modified Jun 17, 2026

CVE-2026-21881 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. 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. EPSS estimates a 0.43% chance of exploitation in the next 30 days.

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

9.1/10

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

EPSS Probability

0.43%

34.6th percentile

Probability of exploitation in the next 30 days. Learn more

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
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-21881?

How severe is CVE-2026-21881?

CVE-2026-21881 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.43% probability of exploitation in the next 30 days.

How do I fix CVE-2026-21881?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-21881?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST