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

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.4%

EPSS score, percentile 30 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

7.7 High

CVSS v4.0 base score, given by the CNA

What should I do?

The fix adds an explicit check in process_feed_response that rejects any HTTP response with a status code in the 201-299 range (i.e. … Full textSolution from the CVE record.

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• 1.3 and earlier

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Solution (from the CVE record)

The fix adds an explicit check in process_feed_response that rejects any HTTP response with a status code in the 201-299 range (i.e., successful responses other than 200) by returning a 403 Forbidden response. This ensures that only responses with exactly status code 200 are subject to the normal filtering pipeline, and all other 2xx responses are blocked before they can reach the MISP instance, closing the bypass vector.

Advisories and patches

• Security patch (Patch)

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

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…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-116372 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 26 Oct 2026.
• The CVE record carries a CVSS v4.0 base score of 7.7 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.4% (percentile 30), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• The credits in the CVE record name Anthropic (Claude) as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

MISP mispguard: Feed responses with 2xx status codes other than 200 bypass filtering rules

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.

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline