CVE-2026-21881 is a critical authentication bypass vulnerability affecting Kanboard versions 1.2.48 and below, a project management software. When REVERSE_PROXY_AUTH is enabled, the application trusts HTTP headers for user authentication without proper verification, allowing an unauthenticated attacker to impersonate any user, including administrators. This vulnerability carries a CVSS score of 9.1 (CRITICAL) due to its network-based attack vector, low complexity, and high impact on confidentiality and integrity. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion, indicating awareness among security professionals.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 1.2.49CPE matchmatch criteria | cpe:2.3:a:kanboard:kanboard:*:*:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.
No media coverage found for this CVE.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.