CVE-2026-77751: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-wwv2-w4mm-82wm
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CWE-22
Published
Advisory Summary

CVE-2026-77751 is a HIGH security vulnerability vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-77751 at a Glance

CVE Identifier CVE-2026-77751
GHSA Identifier GHSA-wwv2-w4mm-82wm
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-77751

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-77751, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A path traversal vulnerability existed in the handling of MISP object template names during STIX 2 import and MISP-to-STIX 2 export. MISP object names are passed to PyMISP's object-template resolution mechanism, which constructs a filesystem path by joining the configured MISP object-template directory, the object name, and definition.json. An object name originating from untrusted STIX or MISP content was not sufficiently restricted before being used in this filesystem path. An attacker able to supply a crafted object name containing path separators or traversal sequences such as ../ could therefore cause template resolution to escape the expected template directory and attempt to load a definition.json file from another location accessible to the process. During STIX 2 import, an attacker-controlled x_misp_name from a custom STIX object could directly reach this template-resolution mechanism. The issue could also become persistent. A malicious object name stored in a MISP event could later be processed again during STIX 2 export. Consequently, content originally introduced in one security context could trigger filesystem access later when the event is exported by a process operating with different or greater privileges. If a suitable definition.json file exists outside the intended template directory, its contents may be interpreted as a MISP object template and fields from that file copied into the converted object. This can result in unintended disclosure of locally accessible data represented by the template file and modification of the resulting object's metadata or semantics. The patches introduce strict validation of object-template names. Valid names are restricted to a single path component containing letters, digits, hyphens, or underscores. Names that do not meet these requirements are replaced with the generic unknown-template name before reaching PyMISP template resolution. The original rejected name is preserved in the object's comment and a warning is generated, preventing traversal while retaining the source information.

References

NVD — CVE-2026-77751 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-77751
Security Fix Commit FIX COMMIT
https://github.com/MISP/misp-stix/commit/a0f54070
Security Fix Commit FIX COMMIT
https://github.com/MISP/misp-stix/commit/a8b6808d

Frequently Asked Questions

What is CVE-2026-77751?
CVE-2026-77751 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-77751?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-77751?
CVE-2026-77751 is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.).
How can I check Maven dependencies for CVE-2026-77751?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wwv2-w4mm-82wm",
  "modified" : "2026-08-21T12:30:31Z",
  "published" : "2026-08-21T12:30:31Z",
  "aliases" : [ "CVE-2026-77751" ],
  "details" : "A path traversal vulnerability existed in the handling of MISP object template names during STIX 2 import and MISP-to-STIX 2 export.\n\nMISP object names are passed to PyMISP's object-template resolution mechanism, which constructs a filesystem path by joining the configured MISP object-template directory, the object name, and definition.json. An object name originating from untrusted STIX or MISP content was not sufficiently restricted before being used in this filesystem path.\n\nAn attacker able to supply a crafted object name containing path separators or traversal sequences such as ../ could therefore cause template resolution to escape the expected template directory and attempt to load a definition.json file from another location accessible to the process.\n\nDuring STIX 2 import, an attacker-controlled x_misp_name from a custom STIX object could directly reach this template-resolution mechanism.\n\nThe issue could also become persistent. A malicious object name stored in a MISP event could later be processed again during STIX 2 export. Consequently, content originally introduced in one security context could trigger filesystem access later when the event is exported by a process operating with different or greater privileges.\n\nIf a suitable definition.json file exists outside the intended template directory, its contents may be interpreted as a MISP object template and fields from that file copied into the converted object. This can result in unintended disclosure of locally accessible data represented by the template file and modification of the resulting object's metadata or semantics.\n\nThe patches introduce strict validation of object-template names. Valid names are restricted to a single path component containing letters, digits, hyphens, or underscores. Names that do not meet these requirements are replaced with the generic unknown-template name before reaching PyMISP template resolution. The original rejected name is preserved in the object's comment and a warning is generated, preventing traversal while retaining the source information.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-77751"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/MISP/misp-stix/commit/a0f54070"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/MISP/misp-stix/commit/a8b6808d"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-21T10:16:39Z"
  }
}