CVE-2025-47911Network attack vector

Service interruption via quadratic HTML parsing

Published Feb 5, 2026 · Updated Feb 5, 2026

Algorithmic complexity in golang.org/x/net/html before 0.45.0 allows remote attackers to exhaust CPU via crafted HTML input. The html.Parse family performs specification-defined tree-construction work that scales quadratically with deeply nested tags instead of bounding document depth. Applications are exposed only when they pass attacker-controlled HTML to these APIs; one request can occupy a worker and interrupt its service.

CVSS severity5.3
Medium
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity in golang.org/x/net/html before 0.45.0 allows remote attackers to exhaust CPU via crafted HTML input. The html.Parse family performs specification-defined tree-construction work that scales quadratically with deeply nested tags instead of bounding document depth. Applications are exposed only when they pass attacker-controlled HTML to these APIs; one request can occupy a worker and interrupt its service.

The record

CVE
CVE-2025-47911
Published
Feb 5, 2026
Updated
Feb 5, 2026
Vendor
golang.org/x/net
Product
golang.org/x/net/html
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 5, 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 <0.45.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

golang.org/x/net · golang.org/x/net/htmlversion=0 <0.45.0

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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

T1499.004Application or System Exploitation

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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