GHSA-r6h4-mm7h-8pmq

Опубликовано: 16 дек. 2025

Источник: github

Github: Прошло ревью

CVSS4: 2.7

Описание

PyMdown Extensions has a ReDOS bug in its Figure Capture extension

Impact

This issue describes a ReDOS bug found within the figure caption extension (pymdownx.blocks.caption ).

In systems that take unchecked user content, this could cause long hangs when processing the data if a malicious payload was crafted.

Patches

This issue is patched in Release 10.16.1.

Workarounds

Some possible workarounds

If users are concerned about this vulnerability and process unknown user content without timeouts or other safeguards in place to prevent really large, malicious content being aimed at systems, the use of pymdownx.blocks.caption could be avoided until the library is updated to 10.16.1+.

References

The original issue https://github.com/facelessuser/pymdown-extensions/issues/2716.

Description

The original issue came through PyMdown Extensions' normal issue tracker instead of the typical security flow: https://github.com/facelessuser/pymdown-extensions/issues/2716. Because this came through the normal issue flow, it was handled as a normal issue. In the future, PyMdown Extensions will ensure such issues, even if prematurely made public through the normal issue flow, are redirected through the typical security process.

The regular expression pattern in question is as follows:

RE_FIG_NUM = re.compile(r'^(\^)?([1-9][0-9]*(?:.[1-9][0-9]*)*)(?= |$)')

The POC was provided by @ShangzhiXu

import re import time regex_pattern = re.compile(r'^(\^)?([1-9][0-9]*(?:.[1-9][0-9]*)*)(?= |$)') for i in range(50, 500, 50): long_string = '1' * i + 'a' start_time = time.time() match = re.match(regex_pattern, long_string) end_time = time.time() print(f"long_string execution time: {end_time - start_time:.6f} s")

The issue with the above pattern is that . was used, which accepts any character when we meant to use \.. The fix was to update the pattern to:

RE_FIG_NUM = re.compile(r'^(\^)?([1-9][0-9]*(?:\.[1-9][0-9]*)*)(?= |$)')

Relevant PR with fix: https://github.com/facelessuser/pymdown-extensions/pull/2717

Version(s) & System Info

Operating System: Any
Python Version: Any

Ссылки

Пакеты

Наименование

pymdown-extensions

pip

Затронутые версииВерсия исправления

< 10.16.1

10.16.1

EPSS

Процентиль: 18%

0.00057

Низкий

2.7 Low

CVSS4

CVE ID

CVE-2025-68142

Дефекты

CWE-1333

Связанные уязвимости

CVE-2025-68142

ubuntu

около 2 месяцев назад

PyMdown Extensions is a set of extensions for the `Python-Markdown` markdown project. Versions prior to 10.16.1 have a ReDOS bug found within the figure caption extension (`pymdownx.blocks.caption`). In systems that take unchecked user content, this could cause long hanges when processing the data if a malicious payload was crafted. This issue is patched in Release 10.16.1. As a workaround, those who process unknown user content without timeouts or other safeguards in place to prevent really large, malicious content being aimed at systems may avoid the use of `pymdownx.blocks.caption` until they're able to upgrade.

CVE-2025-68142

nvd

около 2 месяцев назад

CVE-2025-68142

debian

около 2 месяцев назад

PyMdown Extensions is a set of extensions for the `Python-Markdown` ma ...

EPSS

Процентиль: 18%

0.00057

Низкий

2.7 Low

CVSS4

CVE ID

CVE-2025-68142

Дефекты

CWE-1333