CVE-2023-39318 Improper handling of HTML-like comments in script contexts in html/template

What is CVE-2023-39318?

CVE-2023-39318 is a medium-severity cross-site scripting vulnerability in Golang Go, published on 8 Sep 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

The html/template package does not properly handle HTML-like "" comment tokens, nor hashbang "#!" comment tokens, in <script> contexts. This may cause the template parser to improperly interpret the contents of <script> contexts, causing actions to be improperly escaped. This may be leveraged to perform an XSS attack.

Weakness: CWE-79

Which versions are affected by CVE-2023-39318?

2 open source packages ship an affected version, including golang and stdlib. It affects 1 product.

Products include Golang Go.

How do I fix CVE-2023-39318?

Upgrade golang to a fixed version for your release line: 1.20.8 or 1.21.1.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2023-39318 being exploited?

There is no known exploitation of CVE-2023-39318 in the wild and no public exploit code.

Other vulnerabilities in Golang Go

• CVE-2020-0601 Microsoft Windows CryptoAPI Spoofing Exploited High 8.1
• CVE-2026-27143 Missing bound checks can lead to memory corruption in safe Go in cmd/compile Critical 9.8
• CVE-2024-24790 Unexpected behavior from Is methods for IPv4-mapped IPv6 addresses in net/netip Critical 9.8
• CVE-2023-39320 Arbitrary code execution via go.mod toolchain directive in cmd/go Critical 9.8
• CVE-2023-24540 Improper handling of JavaScript whitespace in html/template Critical 9.8

All Golang Go vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-28694, AZL-28832, AZL-37386, AZL-37494, AZL-52735, AZL-78980 and 8 more.