Cyber Resilience

CVE-2023-26103

Deno ≤ 1.31.0

Public PoC
Published
25 February 2023
Modified
11 March 2025
Patch / advisory
View advisory
CVSS Score v3.1 5.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS Score 0.012 66th percentile
Risk Priority 47 floored blend · peak EPSS

Summary

CVE-2023-26103 is a medium-severity Inefficient Regular Expression Complexity (CWE-1333) vulnerability in Deno Deno. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked in the top 34% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability Data

Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header…

more

can be used to significantly slow down a web socket server.

CWE(s)
CWE-1333

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-55517Same product: Deno Deno
CVE-2024-34346Same product: Deno Deno
CVE-2025-48935Same product: Deno Deno
CVE-2023-28446Same product: Deno Deno
CVE-2024-27931Same product: Deno Deno
CVE-2025-61785Same product: Deno Deno
CVE-2024-27933Same product: Deno Deno
CVE-2026-49411Same product: Deno Deno
CVE-2026-49860Same product: Deno Deno
CVE-2024-32477Same product: Deno Deno

Affected Assets

deno
deno
≤ 1.31.0

Mitigating Controls

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.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent inefficient regex via reviews, static analysis, and safe libraries.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover ReDoS issues in existing code but do not stop their introduction.

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.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect and reject regex patterns with exponential worst-case complexity.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates review of algorithmic efficiency, directly addressing ReDoS-prone regex.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify input-validation rules that limit regex complexity.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles encourage avoidance of computationally expensive constructs such as catastrophic backtracking.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly prohibit or limit the use of inefficient regular expressions.

References