CVE-2026-27142

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.

CVSS Metrics

• v3.1•MEDIUM•Score: 6.1CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Trends

Current EPSS score: 0.01%• Percentile: 2%

Techniques & Countermeasures

• CWE-79•Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

  The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Affected Systems

• go standard library•html/template

  < 1.25.8 | ≥ 1.26.0-0, < 1.26.1

• golang•go

  < 1.25.8 | 1.26.0

• Go•stdlib

  ≥ 1.26.0-0, < 1.26.1

References (4)

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