CVE-2026-103043

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.

CVSS 4.0

8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.6% chance of exploitation in the next 30 days; higher than 47% of CVEs (scores of 2026-10-25)

CWE

CWE-1333

Published

2026-09-29

Modified

2026-10-20

Record from

the NVD, synced 2026-10-21

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

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