CVE-2026-30837
Published: 10 March 2026
Summary
CVE-2026-30837 is a high-severity Inefficient Regular Expression Complexity (CWE-1333) vulnerability in Elysiajs Elysia. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 7.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Threat & Defense at a Glance
Threat & Defense Details
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
ReDoS in public-facing URL validator directly enables application exploitation to exhaust CPU/resources and deny service (T1499.004).
NVD Description
Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. Prior to 1.4.26 , t.String({ format: 'url' }) is vulnerable to ReDoS. Repeating a partial url format (protocol and hostname) multiple times cause regex to…
more
slow down significantly. This vulnerability is fixed in 1.4.26.
Deeper analysisAI
CVE-2026-30837, published on 2026-03-10, affects Elysia, a TypeScript framework used for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.26, the t.String({ format: 'url' }) validator is vulnerable to Regular Expression Denial of Service (ReDoS), classified under CWE-1333. By repeating a partial URL format—such as the protocol and hostname—multiple times in input, the underlying regex engine experiences significant slowdowns. The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), indicating high availability impact with no confidentiality or integrity effects.
Remote attackers can exploit this vulnerability without authentication, privileges, or user interaction by submitting crafted HTTP requests to endpoints that employ the vulnerable URL format validator. Exploitation triggers excessive CPU usage in the regex matching process, leading to degraded performance or complete denial of service on affected servers handling such inputs.
The issue is addressed in Elysia version 1.4.26, which includes a fix for the ReDoS vulnerability. Security advisories recommend upgrading to this version or later. Further details, including a proof-of-concept exploit, are provided in the Elysia GitHub security advisory at GHSA-f45g-68q3-5w8x and a dedicated POC repository at elysia-poc-redos.
Details
- CWE(s)