High severity · published Jul 8, 2026
CVE-2026-59887
linkify-it: Quadratic-complexity DoS via the `mailto:` validator scan-loop on attacker text
7.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 51% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
linkify-it · markdown-it
< 5.0.2 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59887
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59887
Patch
https://github.com/markdown-it/linkify-it/commit/105e5d77f7d119871d2b2d86ed208568eb3e7ffe
Release Notes
https://github.com/markdown-it/linkify-it/releases/tag/5.0.2
Exploit
https://github.com/markdown-it/linkify-it/security/advisories/GHSA-v245-v573-v5vm
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