CVE-2026-21881: critical vulnerability in kanboard
Kanboard is Vulnerable to Reverse Proxy Authentication Bypass
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.1epss 0.5%
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected products
kanboard · kanboardRelated CVEs — kanboard
In the same product, most dangerous first.
CVE-2025-55010CRITICALKanboard Authenticated Admin Remote Code Execution via Unsafe Deserialization of EventsEPSS 1.0%CVE-2024-51748CRITICALRemote code execution through language setting in kanboardEPSS 0.9%CVE-2023-36813HIGHKanboard Authenticated SQL Injections vulnerabilityEPSS 0.9%CVE-2024-51747CRITICALArbitrary File Read and Delete in kanboardEPSS 0.8%CVE-2023-33956MEDIUMParameter based Indirect Object Referencing leading to private file exposure in KanboardEPSS 0.6%CVE-2026-25924HIGHKanboard is Missing Access Control on Plugin Installation leading to Administrative RCEEPSS 0.6%