Medium severity · published Aug 13, 2026
CVE-2026-56858
Fix Javascript regexp context tracking in html/template
6.1
CVSS
0.3%
EPSS
No
On KEV
Description
Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to inject arbitrary content, potentially 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 1.25.13; 1.26.0-0 before 1.26.6; 1.27.0-0 before 1.27.0-rc.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56858
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-56858
go.dev
https://go.dev/cl/807100
go.dev
https://go.dev/issue/80435
groups.google.com
https://groups.google.com/g/golang-announce/c/94pEornpRlI
pkg.go.dev
https://pkg.go.dev/vuln/GO-2026-6091
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