CVE-2026-59887: CWE-407: Inefficient Algorithmic Complexity in markdown-it linkify-it
CVE-2026-59887 is a high-severity vulnerability in the linkify-it library used by markdown-it. Prior to version 5.0.2, the mailto: schema validator could be triggered repeatedly on crafted input, causing quadratic CPU consumption. This inefficient algorithmic complexity leads to a denial-of-service condition by exhausting CPU resources. The issue is fixed in version 5.0.2.
AI Analysis
Technical Summary
The vulnerability in linkify-it affects versions before 5.0.2 where the mailto: schema validator, invoked by the .test() and .match() functions, scans input through src_email_name in lib/re.mjs. This scanning can be triggered at every mailto: occurrence, resulting in O(n^2) CPU consumption on specially crafted user input. This is classified as CWE-407 (Inefficient Algorithmic Complexity). The vulnerability can cause denial of service due to high CPU usage. The fix was introduced in version 5.0.2.
Potential Impact
An attacker can cause denial of service by supplying crafted input that triggers the mailto: schema validator repeatedly, leading to quadratic CPU consumption and potential service disruption. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade to linkify-it version 5.0.2 or later, where this issue is fixed. No other mitigation or temporary workaround is documented. Patch status is not explicitly stated but the fix is included in version 5.0.2.
CVE-2026-59887: CWE-407: Inefficient Algorithmic Complexity in markdown-it linkify-it
Description
CVE-2026-59887 is a high-severity vulnerability in the linkify-it library used by markdown-it. Prior to version 5.0.2, the mailto: schema validator could be triggered repeatedly on crafted input, causing quadratic CPU consumption. This inefficient algorithmic complexity leads to a denial-of-service condition by exhausting CPU resources. The issue is fixed in version 5.0.2.
CVSS v3.1
Score 7.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in linkify-it affects versions before 5.0.2 where the mailto: schema validator, invoked by the .test() and .match() functions, scans input through src_email_name in lib/re.mjs. This scanning can be triggered at every mailto: occurrence, resulting in O(n^2) CPU consumption on specially crafted user input. This is classified as CWE-407 (Inefficient Algorithmic Complexity). The vulnerability can cause denial of service due to high CPU usage. The fix was introduced in version 5.0.2.
Potential Impact
An attacker can cause denial of service by supplying crafted input that triggers the mailto: schema validator repeatedly, leading to quadratic CPU consumption and potential service disruption. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade to linkify-it version 5.0.2 or later, where this issue is fixed. No other mitigation or temporary workaround is documented. Patch status is not explicitly stated but the fix is included in version 5.0.2.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-07T16:40:07.983Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4e7ad4c9d9e3dbe36a7d63
Added to database: 07/08/2026, 16:29:08 UTC
Last enriched: 07/08/2026, 16:43:31 UTC
Last updated: 07/09/2026, 01:11:15 UTC
Views: 7
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