# CVE-2026-21881: kanboard: Kanboard is project management software focused on Kanban methodology

CVE-2026-21881 is fixed in kanboard on 1 platform by DEBIAN-CVE-2026-21881 (version 1.2.49+ds-1), released January 8, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-21881
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0049
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 8, 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | kanboard Debian 14 | 1.2.49+ds-1 | [DEBIAN-CVE-2026-21881](https://patchblox.com/security/data/fix/linux/debian-cve-2026-21881.md) | Jan 8, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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