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TI-2026-17582 Aliases CVE-2026-21881

Kanboard is Vulnerable to Reverse Proxy Authentication Bypass

Priority HIGH 80CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-287.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00486 42nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed kanboard (kanboard): 1.2.49

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
kanboardkanboardbefore 1.2.491.2.49Patch availableCNA
  • kanboard Vendorkanboard Affected before 1.2.49 Fixed in 1.2.49 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:kanboard:kanboard:*:*:*:*:*:*:*:*before 1.2.49Vulnerablekanboard
  • cpe:2.3:a:kanboard:kanboard:*:*:*:*:*:*:*:* Versions before 1.2.49 Vulnerable ·kanboard

Remediation

  • Fix · CNA kanboard (kanboard) Fixed in 1.2.49

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-21881

References

Exploit 1

Patch 1

Other 1

  • TI-2025-34713 Kanboard Authenticated Admin Remote Code Execution via Unsafe Deserialization of Events CVSS 3.1CRITICAL 9.1
  • TI-2024-34653 Remote code execution through language setting in kanboard CVSS 3.1CRITICAL 9.1
  • TI-2024-34652 Arbitrary File Read and Delete in kanboard CVSS 3.1CRITICAL 9.1
  • TI-2025-32655 Kanboard Password Reset Poisoning via Host Header Injection CVSS 3.1HIGH 8.8
  • TI-2026-20954 Kanboard is Missing Access Control on Plugin Installation leading to Administrative RCE CVSS 3.1HIGH 8.5
  • TI-2023-18607 Kanboard Authenticated SQL Injections vulnerability CVSS 3.1HIGH 8.8
See all 47 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences