CVE-2026-25681Network attack vector

Cross-site scripting via unescaped DOCTYPE identifier

Published May 22, 2026 · Updated May 22, 2026

Cross-site scripting in The Go Project golang.org/x/net/html before 0.55.0 allows remote attackers to inject script via crafted HTML. Render fails to escape a greater-than sign recovered from a character reference in a DOCTYPE PUBLIC or SYSTEM identifier, so reparsing terminates the DOCTYPE early and treats following bytes as document data. Exploitation requires an application to sanitize attacker-controlled HTML through a parse-and-render cycle and a user to view the resulting content; the script runs in the application's web origin.

CVSS severity6.1
Medium
EPSS probability0.22%
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 The Go Project golang.org/x/net/html before 0.55.0 allows remote attackers to inject script via crafted HTML. Render fails to escape a greater-than sign recovered from a character reference in a DOCTYPE PUBLIC or SYSTEM identifier, so reparsing terminates the DOCTYPE early and treats following bytes as document data. Exploitation requires an application to sanitize attacker-controlled HTML through a parse-and-render cycle and a user to view the resulting content; the script runs in the application's web origin.

The record

CVE
CVE-2026-25681
Published
May 22, 2026
Updated
May 22, 2026
Vendor
The Go Project
Product
golang.org/x/net/html
Classifications
CWE-1021, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 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 <0.55.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Go Project · golang.org/x/net/htmlversion=0 <0.55.0

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1021Improper Restriction of Rendered UI Layers or Frames
T1189Drive-by Compromise

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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