Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M

CVE-2026-59887linkify-it: Quadratic-complexity DoS via the `mailto:` validator scan-loop on attacker text

High 7.5

In plain English

A high-severity security flaw in linkify-it from markdown-it. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 59.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

linkify-it is a links recognition library with full Unicode support. Prior to 5.0.2, the mailto: schema validator used by .test() and .match() can be invoked at every mailto: occurrence and scan the remaining input through src_email_name in lib/re.mjs, causing O(n^2) CPU consumption on crafted user text. This issue is fixed in version 5.0.2.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	linkify-it	5.0.2	GHSA-v245-v573-v5vm

Affected products (as reported)

Vendor	Product	Versions
markdown-it	linkify-it	< 5.0.2

Weakness: CWE-407 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/markdown-it/linkify-it/security/advisories/GHSA-v245-v573-v5vm x_refsource_CONFIRM
https://github.com/markdown-it/linkify-it/commit/105e5d77f7d119871d2b2d86ed208568eb3e7ffe x_refsource_MISC
https://github.com/markdown-it/linkify-it/releases/tag/5.0.2 x_refsource_MISC