What’s Vulnerable › Vulnerabilities

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

• 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: yes
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-407

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 products

• markdown-it linkify-it: before 5.0.2 — fixed in 5.0.2

How to fix

Upgrade to a fixed version: markdown-it linkify-it 5.0.2. Check the vendor advisory for mitigations.

References

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

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