Medium severity · published May 7, 2026
CVE-2026-39823
Bypass of meta content URL escaping causes XSS in html/template
6.1
CVSS
0.3%
EPSS
No
On KEV
Description
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HT
html/template · Go standard library
before 1.25.10; 1.26.0-0 before 1.26.3 · source: vendor
GO
GO · Golang
before 1.25.10; 1.26.0 before 1.26.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39823
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39823
Patch
https://go.dev/cl/769920
Issue Tracking
https://go.dev/issue/78913
Release Notes
https://groups.google.com/g/golang-announce/c/qcCIEXso47M
Vendor Advisory
https://pkg.go.dev/vuln/GO-2026-4982
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