CVE-2026-35166Network attack vector

Cross-site scripting via pre-escape URL validation

Published Apr 6, 2026 · Updated Apr 6, 2026

Cross-site scripting in Hugo 0.60.0 through 0.159.1 allows attackers to inject script URLs through untrusted Markdown links. The default Goldmark link and image handlers test destinations for dangerous schemes before URL escaping, allowing character references to conceal JavaScript URLs that reach generated href or src attributes. The flaw requires untrusted Markdown and the default renderers; opening the generated page executes the injected script in the site's origin.

CVSS severity5.4
Medium
EPSS probability0.18%
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 Hugo 0.60.0 through 0.159.1 allows attackers to inject script URLs through untrusted Markdown links. The default Goldmark link and image handlers test destinations for dangerous schemes before URL escaping, allowing character references to conceal JavaScript URLs that reach generated href or src attributes. The flaw requires untrusted Markdown and the default renderers; opening the generated page executes the injected script in the site's origin.

The record

CVE
CVE-2026-35166
Published
Apr 6, 2026
Updated
Apr 6, 2026
Vendor
Hugo Authors
Product
Hugo
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 6, 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=>= 0.60.0, < 0.159.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hugo Authors · Hugoversion=>= 0.60.0, < 0.159.2

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/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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