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

> Improper handling of HTML-like comments in script contexts allows attackers to bypass escaping and perform XSS attacks.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 8 Sep 2023
- **Updated:** 13 Feb 2025
- **Also known as:** AZL-28694, AZL-28832, AZL-37386, AZL-37494, AZL-52735, AZL-78980, AZL-98733, BELL-CVE-2023-39318, BIT-golang-2023-39318, DEBIAN-CVE-2023-39318, GHSA-vq7j-gx56-rxjh, GO-2023-2041, MINI-369c-h472-2g25, UBUNTU-CVE-2023-39318

## 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 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2023-39318?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `golang` | Bitnami | All versions | 1.20.8, 1.21.1 |
| `stdlib` | Go | All versions | 1.20.8, 1.21.1 |

Products: 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.

## 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](https://insights.sbomify.com/CVE-2020-0601/): Microsoft Windows CryptoAPI Spoofing (high 8.1, exploited in the wild)
- [CVE-2026-27143](https://insights.sbomify.com/CVE-2026-27143/): Missing bound checks can lead to memory corruption in safe Go in cmd/compile (critical 9.8)
- [CVE-2024-24790](https://insights.sbomify.com/CVE-2024-24790/): Unexpected behavior from Is methods for IPv4-mapped IPv6 addresses in net/netip (critical 9.8)
- [CVE-2023-39320](https://insights.sbomify.com/CVE-2023-39320/): Arbitrary code execution via go.mod toolchain directive in cmd/go (critical 9.8)
- [CVE-2023-24540](https://insights.sbomify.com/CVE-2023-24540/): Improper handling of JavaScript whitespace in html/template (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-39318 and fix it if it is affected.

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

Affected packages and fixed versions:
- golang (Bitnami): affected all versions; fixed in 1.20.8, 1.21.1
- stdlib (Go): affected all versions; fixed in 1.20.8, 1.21.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-39318/ (Markdown: https://insights.sbomify.com/CVE-2023-39318/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39318
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39318
- OSV: https://osv.dev/vulnerability/CVE-2023-39318

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39318/
Summaries are generated and may contain mistakes; the official description above is the record.