CWE-1333: Inefficient Regular Expression Complexity in markdown-it linkify-it (CVE-2026-48801)
linkify-it is a links recognition library with full Unicode support. Prior to 5.0.1, LinkifyIt.prototype.match, the package's primary public API, has O(N²) algorithmic complexity for inputs containing many fuzzy links or emails because the JavaScript-level scan loop re-slices input and re-runs unanchored regex searches on progressively shorter tails. Any service that synchronously renders untrusted Markdown with linkify:true on a request hot path can inherit a worker-process denial of service triggerable by a tens-of-KB request body. This issue is fixed in version 5.0.1.
AI Analysis
Technical Summary
LinkifyIt versions before 5.0.1 contain a vulnerability in the match() API function where the scan loop repeatedly slices the input string and performs unanchored regex searches on progressively shorter substrings. This results in O(N²) algorithmic complexity for inputs with many fuzzy links or emails, causing high CPU consumption and denial-of-service conditions in applications using linkify-it for Markdown rendering.
Potential Impact
The vulnerability can cause denial-of-service due to high CPU usage when processing specially crafted inputs containing many fuzzy links or emails. This affects services that use linkify-it to render untrusted Markdown with linkify enabled, potentially degrading service availability.
Mitigation Recommendations
Upgrade to linkify-it version 5.0.1 or later, where this issue is fixed. Versions prior to 5.0.1 are vulnerable. No other mitigations are indicated.
CWE-1333: Inefficient Regular Expression Complexity in markdown-it linkify-it (CVE-2026-48801)
Description
linkify-it is a links recognition library with full Unicode support. Prior to 5.0.1, LinkifyIt.prototype.match, the package's primary public API, has O(N²) algorithmic complexity for inputs containing many fuzzy links or emails because the JavaScript-level scan loop re-slices input and re-runs unanchored regex searches on progressively shorter tails. Any service that synchronously renders untrusted Markdown with linkify:true on a request hot path can inherit a worker-process denial of service triggerable by a tens-of-KB request body. This issue is fixed in version 5.0.1.
CVSS v4.0
Score 8.7high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
LinkifyIt versions before 5.0.1 contain a vulnerability in the match() API function where the scan loop repeatedly slices the input string and performs unanchored regex searches on progressively shorter substrings. This results in O(N²) algorithmic complexity for inputs with many fuzzy links or emails, causing high CPU consumption and denial-of-service conditions in applications using linkify-it for Markdown rendering.
Potential Impact
The vulnerability can cause denial-of-service due to high CPU usage when processing specially crafted inputs containing many fuzzy links or emails. This affects services that use linkify-it to render untrusted Markdown with linkify enabled, potentially degrading service availability.
Mitigation Recommendations
Upgrade to linkify-it version 5.0.1 or later, where this issue is fixed. Versions prior to 5.0.1 are vulnerable. No other mitigations are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-22p9-wv53-3rq4
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-48801"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- HIGH
- Cvss Version
- 4.0
Threat ID: 6a3ef76a27e9c79719fee800
Added to database: 06/26/2026, 22:04:26 UTC
Last enriched: 07/15/2026, 07:56:37 UTC
Last updated: 07/31/2026, 20:25:37 UTC
Views: 116
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