CVE-2026-77710 in misp-stix
Summary
by MITRE • 08/21/2026
A vulnerability in misp-stix could allow a crafted STIX document to influence security-sensitive MISP attribute metadata during import.
The STIX import logic automatically selected between the internal MISP parser and the external STIX parser based on metadata contained in the STIX document itself. For STIX2, the presence of MISP-specific tool labels could cause a document to be classified as originating from MISP; similarly, STIX1 relied on the document title. These classification indicators are fully controlled by the STIX producer and therefore cannot constitute a trusted indication of the document's origin. The accompanying fix explicitly notes that the parser choice was previously based solely on labels or header titles that any producer could write, and introduces an explicit classification parameter allowing callers to override this detection.
When STIX2 content was handled as an internal MISP export, attributes contained in an x-misp-object were converted by copying the complete x_misp_attributes dictionary and passing it directly to misp_object.add_attribute(). Consequently, a crafted STIX bundle could supply fields that were not part of the expected STIX-to-MISP round-trip format, including security-sensitive properties such as distribution, sharing_group_id, tags, or other MISP attribute fields.
An attacker able to provide a STIX document for import could therefore spoof the markers used to identify MISP-generated content and inject additional attribute properties. This could alter the distribution, sharing restrictions, classification, or semantic metadata of imported attributes, potentially causing information to be shared contrary to the importing organization's policy or influencing downstream processing and automation based on attacker-controlled tags or metadata.
The vulnerability results from dynamically assigning externally supplied object properties without restricting them to an expected set of attributes, matching CWE-915. MITRE specifically describes this weakness as accepting externally influenced fields without controlling which object attributes may be modified and recommends an allow-list, which is the approach implemented by the patch. The parser-selection issue additionally corresponds to CWE-807, because an untrusted value was used to make a security-relevant trust/classification decision.
The attack is also consistent with CAPEC-153 (Input Data Manipulation), in which an attacker controls the structure or flags of supplied data so that the target selects a different processing path or interprets the content differently than intended.
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Analysis
by VulDB Data Team • 08/21/2026
A critical vulnerability exists within the misp-stix integration component, allowing attackers to manipulate security-sensitive metadata during the import process by crafting malicious STIX documents. The core technical flaw stems from an insecure trust model where the system automatically selects between internal MISP parsers and external STIX parsers based on metadata fields contained directly within the incoming document itself. For STIX version 2 formats, the presence of specific tool labels was used to classify a document as originating from MISP, while for STIX version 1, the document title served this purpose. These classification indicators are entirely controlled by the producer of the STIX data and therefore cannot be considered trusted sources regarding the actual origin or integrity of the content. This design flaw enables an attacker to spoof markers that identify MISP-generated content, thereby tricking the system into applying internal processing logic intended for trusted exports rather than standard external imports.
The operational impact is severe because when STIX version 2 content was incorrectly handled as an internal MISP export, attributes contained within x-misp-objects were processed by copying the complete x_misp_attributes dictionary and passing it directly to the misp_object.add_attribute function without sufficient validation. This mechanism allowed a crafted STIX bundle to supply fields that are not part of the expected round-trip format between STIX and MISP. Specifically, an attacker could inject security-sensitive properties such as distribution levels, sharing group identifiers, tags, or other administrative attribute fields. Consequently, this leads to unauthorized modification of how imported data is shared and classified within the threat intelligence platform. Information may be distributed contrary to organizational policy, or downstream automation systems may process alerts based on attacker-controlled metadata, potentially leading to false positives, alert fatigue, or the propagation of malicious indicators under trusted labels.
From a vulnerability classification perspective, this issue aligns with CWE-915, which describes Improperly Controlled Modification of Dynamically-Determined Object Attributes. The weakness lies in accepting externally influenced fields without restricting which object attributes may be modified, failing to implement an allow-list approach for critical metadata fields. Additionally, the parser selection logic corresponds to CWE-807, as it relies on untrusted values to make security-relevant trust and classification decisions. In terms of attack patterns, this scenario is consistent with CAPEC-153, Input Data Manipulation, where an attacker controls the structure or flags of supplied data to force the target system into a different processing path than intended. The MITRE ATT&CK framework would categorize aspects of this exploitation under techniques involving input validation bypasses and potential privilege escalation through metadata manipulation within threat intelligence sharing ecosystems.
The remediation strategy explicitly addresses these flaws by introducing an explicit classification parameter that allows callers to override the automatic detection logic based on document labels or titles. This change ensures that parser selection is determined by trusted configuration rather than untrusted content headers, effectively neutralizing the spoofing vector. Furthermore, the fix enforces stricter validation of attribute fields during import, ensuring that only expected properties are accepted for internal MISP objects. Organizations utilizing this integration must update to the patched version immediately and review their STIX ingestion workflows to ensure no legacy configurations rely on the insecure auto-detection mechanism. Regular audits of imported data sources should also be conducted to verify that external producers adhere to agreed-upon standards, reducing the risk of future manipulation attempts through metadata injection.