CVE-2025-47911: Quadratic parsing complexity in golang.org/x/net/html

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-05 · updated 2026-06-17

Description

The html.Parse function in golang.org/x/net/html has quadratic parsing complexity when processing certain inputs, which can lead to denial of service (DoS) if an attacker provides specially crafted HTML content.

Affected products

Go Html: before 0.45.0 — fixed in 0.45.0
Golang.Org/X/Net: before 0.45.0 — fixed in 0.45.0

How to fix

Upgrade to a fixed version: Go Html 0.45.0; Golang.Org/X/Net 0.45.0. Check the vendor advisory for mitigations.

References

https://github.com/golang/vulndb/issues/4440
https://go.dev/cl/709876
https://groups.google.com/g/golang-announce/c/jnQcOYpiR2c
https://pkg.go.dev/vuln/GO-2026-4440

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