CVE-2026-21881
Kanboard is Vulnerable to Reverse Proxy Authentication Bypass
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.
INFO
Published Date :
Jan. 8, 2026, 2:15 a.m.
Last Modified :
Jan. 8, 2026, 6:15 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Update Kanboard to version 1.2.49 or newer.
- Disable REVERSE_PROXY_AUTH if not required.
- Validate reverse proxy configuration.
- Remove or restrict spoofed HTTP headers.
Public PoC/Exploit Available at Github
CVE-2026-21881 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-21881.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-21881 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-21881
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Security research repository containing published CVEs, proof-of-concept exploits, and detailed vulnerability write-ups.
Python Shell
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The following list is the news that have been mention
CVE-2026-21881 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-21881 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jan. 08, 2026
Action Type Old Value New Value Added Reference https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w -
New CVE Received by [email protected]
Jan. 08, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-287 Added Reference https://github.com/kanboard/kanboard/commit/7af6143e2ad25b5c15549cca8af4341c7ac4e2fc Added Reference https://github.com/kanboard/kanboard/releases/tag/v1.2.49 Added Reference https://github.com/kanboard/kanboard/security/advisories/GHSA-wwpf-3j4p-739w