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Unstructured has Path Traversal via Malicious MSG Attachment that Allows Arbitrary File Write

Critical severity GitHub Reviewed Published Feb 3, 2026 in Unstructured-IO/unstructured • Updated Feb 4, 2026

Package

pip unstructured (pip)

Affected versions

<= 0.18.17

Patched versions

0.18.18

Description

A Path Traversal vulnerability in the partition_msg function allows an attacker to write or overwrite arbitrary files on the filesystem when processing malicious MSG files with attachments.

Impact

An attacker can craft a malicious .msg file with attachment filenames containing path traversal sequences (e.g.,
../../../etc/cron.d/malicious). When processed with process_attachments=True, the library writes the attachment to an
attacker-controlled path, potentially leading to:

  • Arbitrary file overwrite
  • Remote code execution (via overwriting configuration files, cron jobs, or Python packages)
  • Data corruption
  • Denial of service

Affected Functionality

The vulnerability affects the MSG file partitioning functionality when process_attachments=True is enabled.

Vulnerability Details

The library does not sanitize attachment filenames in MSG files before using them in file write operations, allowing directory
traversal sequences to escape the intended output directory.

Workarounds

Until patched, users can:

  • Set process_attachments=False when processing untrusted MSG files
  • Avoid processing MSG files from untrusted sources
  • Implement additional filename validation before processing

References

@william-u10d william-u10d published to Unstructured-IO/unstructured Feb 3, 2026
Published to the GitHub Advisory Database Feb 3, 2026
Reviewed Feb 3, 2026
Published by the National Vulnerability Database Feb 4, 2026
Last updated Feb 4, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(31st percentile)

Weaknesses

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. Learn more on MITRE.

External Control of File Name or Path

The product allows user input to control or influence paths or file names that are used in filesystem operations. Learn more on MITRE.

CVE ID

CVE-2025-64712

GHSA ID

GHSA-gm8q-m8mv-jj5m

Source code

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