CVE-2026-56858: Go Standard Library Html/template

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS.

Affected products

• Go Standard Library Html/template: before 1.25.13 (fixed in 1.25.13); from 1.26.0-0, before 1.26.6 (fixed in 1.26.6); from 1.27.0-0, before 1.27.0-rc.3 (fixed in 1.27.0-rc.3)

Published 2026-08-13. Last modified 2026-09-03.