# CVE-2018-17848: golang.org/x/net/html Improper Validation of Array Index vulnerability

> A crafted HTML input causes a runtime panic in the Go html package, leading to a denial of service for applications using the parser.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Oct 2018
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-mv93-wvcp-7m7r

## What is CVE-2018-17848?

CVE-2018-17848 is a high-severity denial of service vulnerability in Fedoraproject Fedora, published on 1 Oct 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The html package (aka x/net/html) through 2018-09-25 in Go mishandles <math><template><mn><b></template>, leading to a "panic: runtime error" (index out of range) in (*insertionModeStack).pop in node.go, called from inHeadIM, during an html.Parse call.

Weakness: CWE-129 (Improper Validation of Array Index)

## Which versions are affected by CVE-2018-17848?

2 open source packages ship an affected version, including golang.org/x/net. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `golang.org/x/net` | Go | All versions | 0.0.0-20190125002852-4b62a64f59f7 |
| `golang.org/x/net` | Go | All versions | 0.0.0-20190125002852-4b62a64f59f7 |

Products: Fedoraproject Fedora, Golang Net.

## How do I fix CVE-2018-17848?

Upgrade golang.org/x/net to 0.0.0-20190125002852-4b62a64f59f7 or later.

## Is CVE-2018-17848 being exploited?

There is no known exploitation of CVE-2018-17848 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-17848 and fix it if it is affected.

What it is: CVE-2018-17848 is a high-severity denial of service vulnerability in Fedoraproject Fedora, published on 1 Oct 2018. 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-2018-17848 in the wild and no public exploit code.

Affected packages and fixed versions:
- golang.org/x/net (Go): affected all versions; fixed in 0.0.0-20190125002852-4b62a64f59f7
- golang.org/x/net (Go): affected all versions; fixed in 0.0.0-20190125002852-4b62a64f59f7

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-2018-17848/ (Markdown: https://insights.sbomify.com/CVE-2018-17848/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-17848
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-17848
- OSV: https://osv.dev/vulnerability/CVE-2018-17848

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-17848/
Summaries are generated and may contain mistakes; the official description above is the record.