CVE-2026-30837
Elysiajs Elysia ≤ 1.4.26
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
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 Endpoint Denial of Service (T1499); ranked at the 40th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
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.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-10860
Vulnerability Data
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover inefficient regex patterns via performance or static analysis.
Development standards and tools can require safe regex construction and forbid known exponential patterns.
Denial-of-service protections limit resource exhaustion caused by expensive regex evaluation.
Input validation can constrain data that would otherwise trigger worst-case regex complexity.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect and reject regex patterns with exponential worst-case complexity.
Secure development lifecycle mandates review of algorithmic efficiency, directly addressing ReDoS-prone regex.
Application security requirements can specify input-validation rules that limit regex complexity.
Secure architecture principles encourage avoidance of computationally expensive constructs such as catastrophic backtracking.
Secure coding standards explicitly prohibit or limit the use of inefficient regular expressions.