What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-29 · updated 2026-10-20
• Weakness: CWE-1333

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.

Affected products

• alexcorvi anchorme: through 3.0.8

References

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

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