CVE-2025-68142Public exploitNetwork attack vector

Markdown processing hang via unescaped caption regex

Published Dec 16, 2025 · Updated Dec 16, 2025

Regular expression denial of service in PyMdown Extensions before 10.16.1 allows remote attackers to hang Markdown processing. The RE_FIG_NUM pattern in pymdownx.blocks.caption uses an unescaped dot where a literal period is required, causing excessive backtracking on crafted figure numbers. The caption extension must process unchecked user content, and the resulting CPU consumption can stall the calling application without timeouts or input limits.

CVSS severity5.3
Medium
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in PyMdown Extensions before 10.16.1 allows remote attackers to hang Markdown processing. The RE_FIG_NUM pattern in pymdownx.blocks.caption uses an unescaped dot where a literal period is required, causing excessive backtracking on crafted figure numbers. The caption extension must process unchecked user content, and the resulting CPU consumption can stall the calling application without timeouts or input limits.

The record

CVE
CVE-2025-68142
Published
Dec 16, 2025
Updated
Dec 16, 2025
Vendor
facelessuser
Product
PyMdown Extensions
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 16, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 10.16.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

facelessuser · PyMdown Extensionsversion=< 10.16.1

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
2.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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