CVE-2026-5160Network attack vector

Cross-site scripting via pre-normalization URL validation

Published Apr 15, 2026 · Updated Apr 15, 2026

Cross-site scripting in goldmark renderer/html before 1.7.17 allows remote attackers to execute browser scripts through crafted Markdown URLs. The link and image renderers call IsDangerousURL before URLEscape resolves character references, so an encoded JavaScript scheme passes validation and is emitted into HTML. An application must render attacker-controlled Markdown and a user must activate the emitted link; execution occurs in that application's browser origin.

CVSS severity5.1
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in goldmark renderer/html before 1.7.17 allows remote attackers to execute browser scripts through crafted Markdown URLs. The link and image renderers call IsDangerousURL before URLEscape resolves character references, so an encoded JavaScript scheme passes validation and is emitted into HTML. An application must render attacker-controlled Markdown and a user must activate the emitted link; execution occurs in that application's browser origin.

The record

CVE
CVE-2026-5160
Published
Apr 15, 2026
Updated
Apr 15, 2026
Vendor
Yusuke Inuzuka
Product
goldmark renderer/html
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2026Record 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 <1.7.17

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yusuke Inuzuka · goldmark renderer/htmlversion=0 <1.7.17

Published CVSS scores

6.1SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.1SnykCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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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