CVE-2026-77755

Technical Description

A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.

The STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.

Additionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.

An attacker able to pr

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References