What’s Vulnerable › Vulnerabilities

CVE-2026-27142: URLs in meta content attribute actions are not escaped in html/template

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-06 · updated 2026-06-17
• Weakness: CWE-79

Description

Actions which insert URLs into the content attribute of HTML meta tags are not escaped. This can allow XSS if the meta tag also has an http-equiv attribute with the value "refresh". A new GODEBUG setting has been added, htmlmetacontenturlescape, which can be used to disable escaping URLs in actions in the meta content attribute which follow "url=" by setting htmlmetacontenturlescape=0.

Affected products

• Go: before 1.25.8; 1.26.0 — fixed in 1.25.8
• Go Stdlib: before 1.25.8; from 1.26.0-0 before 1.26.1 — fixed in 1.25.8, 1.26.1

How to fix

Upgrade to a fixed version: Go 1.25.8; Go Stdlib 1.25.8, 1.26.1. Check the vendor advisory for mitigations.

References

• https://go.dev/cl/752081
• https://go.dev/issue/77954
• https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk
• https://pkg.go.dev/vuln/GO-2026-4603

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