CVE-2018-25110Public exploitNetwork attack vector

Parser hang via catastrophic regex backtracking

Published May 23, 2025 · Updated May 23, 2025

Regular expression denial of service in Marked before 0.3.17 allows remote attackers to hang Markdown parsing with crafted input. In lib/marked.js, the block HTML-closing, inline tag, no-link, and link-inside regular expressions permit ambiguous repeated matches that backtrack catastrophically on nested brackets or repeated tag attributes. Any application that passes attacker-controlled Markdown to the parser can consume a processing thread for an extended period, interrupting service availability.

CVSS severity6.9
Medium
EPSS probability0.58%
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 Marked before 0.3.17 allows remote attackers to hang Markdown parsing with crafted input. In lib/marked.js, the block HTML-closing, inline tag, no-link, and link-inside regular expressions permit ambiguous repeated matches that backtrack catastrophically on nested brackets or repeated tag attributes. Any application that passes attacker-controlled Markdown to the parser can consume a processing thread for an extended period, interrupting service availability.

The record

CVE
CVE-2018-25110
Published
May 23, 2025
Updated
May 23, 2025
Vendor
MarkedJS
Product
Marked
Classifications
CWE-1333, CAPEC-492, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 23, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=0 <0.3.17

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MarkedJS · Markedversion=0 <0.3.17

Published CVSS scores

6.9CheckmarxCVSS: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:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
CAPEC-492Regular Expression Exponential Blowup
T1499Endpoint Denial of Service

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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