Authentication Bypass Vulnerability in Kanboard Project Management Software
CVE-2026-21881

9.1CRITICAL

Key Information:

Vendor

Kanboard

Status
Kanboard
Vendor
CVE Published:
8 January 2026

What is CVE-2026-21881?

Kanboard, a popular project management tool utilizing Kanban methodology, is susceptible to an authentication bypass vulnerability when the REVERSE_PROXY_AUTH feature is enabled. This flaw arises because the application fails to validate whether HTTP headers originate from a trusted reverse proxy, allowing potential attackers to send falsified HTTP headers. This loophole enables them to impersonate any user, including administrative accounts, posing serious security risks. Users are encouraged to upgrade to version 1.2.49, which addresses this issue.

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Deploy the Patch

Affected Version(s)

kanboard < 1.2.49

References

https://github.com/kanboard/kanboard/security/advisories/...
x_refsource_CONFIRM
https://github.com/kanboard/kanboard/commit/7af6143e2ad25...
x_refsource_MISC
https://github.com/kanboard/kanboard/releases/tag/v1.2.49
x_refsource_MISC

CVSS V3.1

Score:
9.1
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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