CVE-2026-77761
MediumCVSS 6.3Exploitation Probability (EPSS)
Low risk30th percentile - higher than 30% of all known CVEs
Summary
A vulnerability in the misp-stix library stems from incomplete clearing of parser state between STIX document conversions. Reusing the same parser instance can cause data from a previously processed document (e.g., galaxies, DNS records, titles, timestamps) to be incorporated into the MISP event generated from a subsequent document. The issue affects both STIX 1 and STIX 2 parsers.
Risk Assessment
The risk involves contamination of generated threat intelligence, potentially leading to incorrect associations, misleading contextual information, or attribution of unrelated indicators to an event. In environments with different access controls, retained state could result in limited disclosure of information from a previously processed document.
Recommendation
Avoid reusing misp-stix parser instances for independent STIX documents — create a new parser for each file. If reuse is necessary, ensure the vendor provides a patch and apply it promptly.
Other vulnerabilities in misp-stix
See all- CVE-2026-77755High
A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents. The import code used sys.exit() to handle errors, causing unexpected process termination, and did not limit input size, leading to excessive memory and CPU consumption.
- CVE-2026-77710Medium
A vulnerability in misp-stix allows an attacker to supply a crafted STIX document that can influence security-sensitive MISP attribute metadata during import. The parser selection was based on untrusted indicators (tool labels or document title), enabling spoofing of MISP-origin content. Additionally, attributes from x-misp-object were copied without restrictions, allowing injection of unexpected fields.
Original NVD description (English source)
A parser state isolation vulnerability in misp-stix could cause data from a previously processed STIX document to be retained and incorporated into the MISP event generated from a subsequent document when the same parser instance is reused. Several STIX 1 and STIX 2 parser components maintained per-document state that was not completely cleared between conversions. In the STIX 2 parser, galaxy and galaxy-cluster information, including custom galaxy clusters, could survive a parser reset and subsequently be associated with objects from another bundle. The STIX 1 parsers were affected by the same underlying state-management issue. Depending on the parser type, retained information could include galaxies, references, passive DNS bookkeeping, package titles, dates, and timestamps. As a result, parsing a second STIX package with an already-used parser could produce a MISP event containing information that was present only in the previously processed package. For example, a generated event could inherit passive DNS records from an earlier document, reference unrelated galaxy information, combine titles from different packages, or use timestamps originating from another conversion. The issue primarily affects applications using the misp-stix API directly and reusing parser instances across independent STIX documents. Normal conversion entry points that instantiate a new parser for each file are not affected by this particular reuse scenario. An attacker able to influence documents processed by such a long-lived parser could potentially cause information from one conversion to contaminate a subsequent MISP event. This can affect the integrity of generated threat intelligence, resulting in incorrect associations, misleading contextual information, or unrelated indicators being attributed to an event. In environments where consecutive documents have different access controls or distribution scopes, the retained state could additionally result in limited disclosure of information from a previously processed document. Successful exploitation depends on the consuming application reusing the same parser instance and on the ordering of processed documents, which increases attack complexity. No direct availability impact or code execution is involved.