Service interruption via inefficient URL-format regex
Published Mar 10, 2026 · Updated Mar 10, 2026
Regular expression denial of service in Elysia before 1.4.26 allows remote attackers to interrupt service through crafted URL values. The fullFormats.url validator used by t.String({ format: 'url' }) applies an inefficient regular expression to repeated partial protocol-and-hostname strings, producing superlinear validation time. Reachability requires an application route to validate attacker-controlled input with the URL format; sufficiently long values consume CPU and stall request processing.
Summary
What happened
Regular expression denial of service in Elysia before 1.4.26 allows remote attackers to interrupt service through crafted URL values. The fullFormats.url validator used by t.String({ format: 'url' }) applies an inefficient regular expression to repeated partial protocol-and-hostname strings, producing superlinear validation time. Reachability requires an application route to validate attacker-controlled input with the URL format; sufficiently long values consume CPU and stall request processing.
The record
- CVE
- CVE-2026-30837
- Published
- Mar 10, 2026
- Updated
- Mar 10, 2026
- Vendor
- ElysiaJS
- Product
- Elysia
- Classifications
- CWE-1333, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 10, 2026CVE publishedPublication date reported by the CVE source.
- Mar 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.4.26
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Elysia format:url ReDoS PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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