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CVE-2026-21881

Kanboard is Vulnerable to Reverse Proxy Authentication Bypass

Published: Jan 8, 2026Updated: Jan 20, 2026 Sources: CVE List NVDCWE-287
NVD MITRE
9.1CVSSCRITICAL
EPSS Score
0.4%
Top 65.6%
CISA KEV
Not in KEV
Exploits
1 Known
Remediation
Patch Available

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 Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-287

Affected Products

kanboardkanboard
On-prem
Enterprise Software / collaboration-groupware
kanboardoss-projectEnterprise Softwareaka kanban board

Attack Graph

Products CVE Techniques Tactics

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Exploitability

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
View detailed technique mapping

References

https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc
github.com
https://github.com/kanboard/kanboard/releases/tag/v1.2.49
github.com
https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w
github.com

Timeline

Published
Jan 8, 2026
Last Updated
Jan 20, 2026

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