# CVE-2023-39663: MathJax Regular expression Denial of Service (ReDoS)

> Regular expression denial of service in MathJax library, though vendor disputes risk as regexes are not applied to user input.

- **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:** No
- **Published:** 29 Aug 2023
- **Updated:** 2 Oct 2024
- **Also known as:** GHSA-v638-q856-grg8, UBUNTU-CVE-2023-39663

## What is CVE-2023-39663?

CVE-2023-39663 is a high-severity denial of service vulnerability in n/a, published on 29 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Mathjax up to v2.7.9 was discovered to contain two Regular expression Denial of Service (ReDoS) vulnerabilities in MathJax.js via the components pattern and markdownPattern. NOTE: the vendor disputes this because the regular expressions are not applied to user input; thus, there is no risk.

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2023-39663?

2 open source packages ship an affected version, including mathjax. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mathjax` | npm | All versions to 2.7.9 | None |
| `mathjax` | npm | All versions to 2.7.9 | None |

Products: Mathjax Mathjax.

## How do I fix CVE-2023-39663?

No fix has been published for CVE-2023-39663 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-39663 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-39663 exists.

## Other vulnerabilities in n/a

- [CVE-2018-1999024](https://insights.sbomify.com/CVE-2018-1999024/): Macro in MathJax running untrusted Javascript within a web browser (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-39663 and fix it if it is affected.

What it is: CVE-2023-39663 is a high-severity denial of service vulnerability in n/a, published on 29 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-39663 exists.

Affected packages and fixed versions:
- mathjax (npm): affected all versions up to 2.7.9; no fix listed
- mathjax (npm): affected all versions up to 2.7.9; no fix listed

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-2023-39663/ (Markdown: https://insights.sbomify.com/CVE-2023-39663/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39663
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39663
- OSV: https://osv.dev/vulnerability/CVE-2023-39663

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39663/
Summaries are generated and may contain mistakes; the official description above is the record.