CVE-2026-39823

Bypass of meta content URL escaping causes XSS in html/template

CVSS 6.1 MEDIUMEPSS 0.3%

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 6.1EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

07 May 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta> tag's <content> attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the <content> attribute, the escaper would fail to similarly escape it, leading to XSS.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

Go standard library · html/template

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References

https://go.dev/cl/769920 https://go.dev/issue/78913 https://groups.google.com/g/golang-announce/c/qcCIEXso47M https://pkg.go.dev/vuln/GO-2026-4982