html/template XSS via unescaped '/' (<=1.25.12, <=1.26.5, <=1.27.0-rc.2)
CVE-2026-56858 Published on August 13, 2026
Fix Javascript regexp context tracking in html/template
Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS.
Vulnerability Analysis
CVE-2026-56858 is exploitable with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a XSS Vulnerability?
The software 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.
CVE-2026-56858 has been classified to as a XSS vulnerability or weakness.
Affected Versions
Go standard library html/template:- Before 1.25.13 is affected.
- Version 1.26.0-0 and below 1.26.6 is affected.
- Version 1.27.0-0 and below 1.27.0-rc.3 is affected.