# CVE-2023-30533: Prototype Pollution in sheetJS

> Prototype pollution in SheetJS allows attackers to manipulate object prototypes via crafted files, potentially leading to code execution or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Apr 2023
- **Updated:** 4 Feb 2025
- **Also known as:** CLEANSTART-2026-WV02485, GHSA-4r6h-8v6p-xvw6, ROOT-APP-NPM-CVE-2023-30533

## What is CVE-2023-30533?

CVE-2023-30533 is a high-severity vulnerability in n/a, published on 24 Apr 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

SheetJS Community Edition before 0.19.3 allows Prototype Pollution via a crafted file. In other words. 0.19.2 and earlier are affected, whereas 0.19.3 and later are unaffected.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2023-30533?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `xlsx` | npm | All versions | None |
| `xlsx` | npm | All versions | None |

Products: Sheetjs Sheetjs.

## How do I fix CVE-2023-30533?

Upgrade to a fixed version.

## Is CVE-2023-30533 being exploited?

There is no known exploitation of CVE-2023-30533 in the wild and no public exploit code.

Public exploit code:

- There were no proper POCs for CVE-2023-30533 so I made one. (Reported by Vsevolod Kokorin) (github_poc): https://github.com/BenEdridge/CVE-2023-30533
- SheetJS xlsx 0.18.5 fork with CVE-2023-30533 and CVE-2024-22363 fixes (github_poc): https://github.com/weareu/xlsx

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-30533 and fix it if it is affected.

What it is: CVE-2023-30533 is a high-severity vulnerability in n/a, published on 24 Apr 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2023-30533 in the wild and no public exploit code.

Affected packages and fixed versions:
- xlsx (npm): affected all versions; no fix listed
- xlsx (npm): affected all versions; 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-2023-30533/ (Markdown: https://insights.sbomify.com/CVE-2023-30533/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-30533
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-30533
- OSV: https://osv.dev/vulnerability/CVE-2023-30533

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-30533/
Summaries are generated and may contain mistakes; the official description above is the record.