# CVE-2023-24539: Improper sanitization of CSS values in html/template

> Attackers can inject unexpected HTML via CSS contexts in Go templates, potentially leading to cross-site scripting or code execution.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 May 2023
- **Updated:** 24 Jan 2025
- **Also known as:** AZL-26614, AZL-26625, AZL-37307, AZL-37362, AZL-52668, AZL-79046, AZL-98802, BIT-golang-2023-24539, DEBIAN-CVE-2023-24539, GHSA-3q6h-q44p-xw88, GO-2023-1751, MINI-rq2v-65hp-v8v9

## What is CVE-2023-24539?

CVE-2023-24539 is a high-severity cross-site scripting vulnerability in Golang Go, published on 11 May 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Angle brackets (<>) are not considered dangerous characters when inserted into CSS contexts. Templates containing multiple actions separated by a '/' character can result in unexpectedly closing the CSS context and allowing for injection of unexpected HTML, if executed with untrusted input.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2023-24539?

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 | 1.19.9, 1.20.4 |
| `stdlib` | Go | All versions | 1.19.9, 1.20.4 |

Products: Golang Go.

## How do I fix CVE-2023-24539?

Upgrade golang to a fixed version for your release line: 1.19.9 or 1.20.4.

## Is CVE-2023-24539 being exploited?

There is no known exploitation of CVE-2023-24539 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-2023-24539 and fix it if it is affected.

What it is: CVE-2023-24539 is a high-severity cross-site scripting vulnerability in Golang Go, published on 11 May 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-24539 in the wild and no public exploit code.

Affected packages and fixed versions:
- golang (Bitnami): affected all versions; fixed in 1.19.9, 1.20.4
- stdlib (Go): affected all versions; fixed in 1.19.9, 1.20.4

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-2023-24539/ (Markdown: https://insights.sbomify.com/CVE-2023-24539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-24539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-24539
- OSV: https://osv.dev/vulnerability/CVE-2023-24539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-24539/
Summaries are generated and may contain mistakes; the official description above is the record.