CVE-2026-91819: Input Validation Flaw

Description

Affected versions of MISP rely on CakePHP request-method override processing in a way that can disable CSRF and form-security validation. CakePHP honors a _method field or X-HTTP-Method-Override header by rewriting the effective request method. For override values outside the normal write verbs POST, PUT, PATCH, and DELETE, CakePHP also clears the parsed request body. MISP’s security component then determines whether to perform _validatePost() and _validateCsrf() based on whether request data remains. With a value such as: _method=GET the body becomes empty before those checks run, so both protections are skipped. A cross-site form containing only that override can therefore reach actions whose parameters are taken from the URL rather than the request body Version affected: ≤2.5.45

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EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-352 Cross-Site Request Forgery

References

Other References

https://github.com/MISP/MISP/commit/29af008c4

Frequently Asked Questions

What is CVE-2026-91819? +

Affected versions of MISP rely on CakePHP request-method override processing in a way that can disable CSRF and form-security validation. CakePHP honors a _method field or X-HTTP-Method-Override header by rewriting the effective request method. For override values outside the normal write verbs POST, PUT, PATCH, and DELETE, CakePHP also clears the parsed request body. MISP’s security component then determines whether to perform _validatePost() and _validateCsrf() based on whether request data remains. With a value such as: _method=GET the body becomes empty before those checks run, so both protections are skipped. A cross-site form containing only that override can therefore reach actions whose parameters are taken from the URL rather than the request body Version affected: ≤2.5.45

How do I check if I'm vulnerable to CVE-2026-91819? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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