What is CVE-2026-39826?

CVE-2026-39826 is a medium-severity vulnerability in Golang Go, classified under Improper Encoding or Escaping of Output. CVSS score: 6.1/10. Published 2026-05-07.

How severe is CVE-2026-39826?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Vulnerability in Golang Go

CVE-2026-39826

If a trusted template author were to write a <script> tag containing an empty 'type' attribute or a 'type' attribute with an ASCII whitespace, the execution of the template would incorrectly escape any data passed into the <script> block.

Published 2026-05-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.004 (30.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 30.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000

Affected products

Golang Go
Go Standard Library Html/template — versions 0, 1.26.0-0

Weakness classification (CWE)

CWE-116 — Improper Encoding or Escaping of Output

References

go.dev/issue/78981 (Patch)
go.dev/cl/771180 (Patch)
groups.google.com/g/golang-announce/c/qcCIEXso47M (Release Notes)
pkg.go.dev/vuln/GO-2026-4980 (Vendor Advisory)

Frequently asked questions

What is CVE-2026-39826?: CVE-2026-39826 is a medium-severity vulnerability in Golang Go, classified under Improper Encoding or Escaping of Output. CVSS score: 6.1/10. Published 2026-05-07.
How severe is CVE-2026-39826?: Medium severity. CVSS v3 base score is 6.1 out of 10.