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PYSEC-2026-558
No affected components available
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=Falsewhen processing untrusted MSG files - Avoid processing MSG files from untrusted sources
- Implement additional filename validation before processing
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Active exploitation in the wild has been confirmed. Immediate patching or mitigation is required.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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