CVE-2023-24538

CriticalCVSS 9.8

Published: 06/04/2023(UTC)Updated: 17/06/2026(UTC)Translated: 05/11/2026(UTC)NVD NIST

Summary

Templates do not properly consider backticks (`) as Javascript string delimiters, and do not escape them as expected. If a template contains a Go template action within a Javascript template literal, the contents of the action can be used to terminate the literal, injecting arbitrary Javascript code into the Go template. With the fix, Template.Parse returns an Error when it encounters templates like this.

Risk Assessment

This may allow injection of arbitrary JavaScript code into the generated template, creating a risk of malicious client-side code execution.

Recommendation

Update the Go template library to a version containing the fix and avoid Go template actions inside JavaScript template literals.

Other vulnerabilities in Go template library

CVE-2023-24540Critical
Not all valid JavaScript whitespace characters are considered to be whitespace. Templates containing whitespace characters outside of the character set "\t\n\f\r\u0020\u2028\u2029" in JavaScript contexts that also contain actions may not be properly sanitized during execution.

Original NVD description (English source)

Templates do not properly consider backticks (`) as Javascript string delimiters, and do not escape them as expected. Backticks are used, since ES6, for JS template literals. If a template contains a Go template action within a Javascript template literal, the contents of the action can be used to terminate the literal, injecting arbitrary Javascript code into the Go template. As ES6 template literals are rather complex, and themselves can do string interpolation, the decision was made to simply disallow Go template actions from being used inside of them (e.g. "var a = {{.}}"), since there is no obviously safe way to allow this behavior. This takes the same approach as github.com/google/safehtml. With fix, Template.Parse returns an Error when it encounters templates like this, with an ErrorCode of value 12. This ErrorCode is currently unexported, but will be exported in the release of Go 1.21. Users who rely on the previous behavior can re-enable it using the GODEBUG flag jstmpllitinterp=1, with the caveat that backticks will now be escaped. This should be used with caution.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS