CVE-2026-24486

Summary

A Path Traversal vulnerability exists when using non-default configuration options UPLOAD_DIR and UPLOAD_KEEP_FILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename.

Details

When UPLOAD_DIR is set and UPLOAD_KEEP_FILENAME is True, the library constructs the file path using os.path.join(file_dir, fname). Due to the behavior of os.path.join(), if the filename begins with a /, all preceding path components are discarded:

os.path.join("/upload/dir", "/etc/malicious") == "/etc/malicious"

This allows an attacker to bypass the intended upload directory and write files to arbitrary paths.

Affected Configuration

Projects are only affected if all of the following are true:

• UPLOAD_DIR is set
• UPLOAD_KEEP_FILENAME is set to True
• The uploaded file exceeds MAX_MEMORY_FILE_SIZE (triggering a flush to disk)

The default configuration is not vulnerable.

Impact

Arbitrary file write to attacker-controlled paths on the filesystem.

Mitigation

Upgrade to version 0.0.22, or avoid using UPLOAD_KEEP_FILENAME=True in project configurations.

A streaming multipart parser for Python

Security Fix(es):

Python-Multipart is a streaming multipart parser for Python. Prior to version 0.0.22, a Path Traversal vulnerability exists when using non-default configuration options UPLOAD_DIR and UPLOAD_KEEP_FILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename. Users should upgrade to version 0.0.22 to receive a patch or, as a workaround, avoid using UPLOAD_KEEP_FILENAME=True in project configurations.(CVE-2026-24486)

Summary

A Path Traversal vulnerability exists when using non-default configuration options UPLOAD_DIR and UPLOAD_KEEP_FILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename.

Details

When UPLOAD_DIR is set and UPLOAD_KEEP_FILENAME is True, the library constructs the file path using os.path.join(file_dir, fname). Due to the behavior of os.path.join(), if the filename begins with a /, all preceding path components are discarded:

os.path.join("/upload/dir", "/etc/malicious") == "/etc/malicious"

This allows an attacker to bypass the intended upload directory and write files to arbitrary paths.

Affected Configuration

Projects are only affected if all of the following are true:

• UPLOAD_DIR is set
• UPLOAD_KEEP_FILENAME is set to True
• The uploaded file exceeds MAX_MEMORY_FILE_SIZE (triggering a flush to disk)

The default configuration is not vulnerable.

Impact

Arbitrary file write to attacker-controlled paths on the filesystem.

Mitigation

Upgrade to version 0.0.22, or avoid using UPLOAD_KEEP_FILENAME=True in project configurations.

Root has patched CVE-2026-24486 in the python-multipart package for Root:PyPI. Multiple fixed versions available.

Python-Multipart is a streaming multipart parser for Python. Prior to version 0.0.22, a Path Traversal vulnerability exists when using non-default configuration options UPLOAD_DIR and UPLOAD_KEEP_FILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename. Users should upgrade to version 0.0.22 to receive a patch or, as a workaround, avoid using UPLOAD_KEEP_FILENAME=True in project configurations.

TuxCare rebuilt python-multipart to address 1 CVE. Fixed in 0.0.6.post7+tuxcare.

This update for python-python-multipart fixes the following issues:

• CVE-2026-24486: Fixed non-default configuration options can lead to path traversal (bsc#1257301).

This update for python-python-multipart fixes the following issues:

• CVE-2026-24486: Fixed non-default configuration options can lead to path traversal (bsc#1257301).

This update for python-python-multipart fixes the following issues:

• CVE-2026-24486: Fixed non-default configuration options can lead to path traversal (bsc#1257301).

It was discovered that Python-Multipart incorrectly handled certain regular expressions. An attacker could possibly use this issue to cause Python-Multipart to consume excessive resources, leading to a regular expression denial of service. This issue only affected Ubuntu 22.04 LTS. (CVE-2024-24762)

It was discovered that Python-Multipart did not properly sanitize line breaks during user input. An attacker could use this issue to send arbitrary input, thus preventing other requests from being processed, resulting in a denial of service. This issue was only fixed in Ubuntu 24.04 LTS. (CVE-2024-53981)

It was discovered that Python-Multipart was vulnerable to path traversal attacks. An attacker could possibly craft and upload files outside the target directory, resulting in remote code execution. (CVE-2026-24486)