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    CVE-2023-26103

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

    Published:Feb 25, 2023
    Last Modified:Mar 11, 2025
    EPS:Feb 25, 2023
    EPSS Score:0.00092
    CVSS Score:5.3

    Affected Products

    Vendor
    Deno
    Product
    Deno

    Exploits

    https://security.snyk.io/vuln/SNYK-RUST-DENO-3315970https://security.snyk.io/vuln/SNYK-RUST-DENO-3315970

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-492 Regular Expression Exponential Blowup

    Related CVEs

    CVE-2026-55517 (CVSS 4.3) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.5, a Deno program that opens a client …
    CVE-2026-44726 (CVSS 7.4) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. From 2.0.0 until 2.7.8, a flaw in Deno's Node.js tl…
    CVE-2026-49401 (CVSS 7.3) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.14, Deno's permission system enforces …
    CVE-2026-49402 (CVSS 8.1) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.10, Deno's node:child_process implemen…
    CVE-2026-49406 (CVSS 5.5) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.12, when Deno was run in BYONM mode (n…
    CVE-2026-49411 (CVSS 6.5) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.0, the Node.js compatibility TCP path …
    CVE-2026-49983 (CVSS 5.2) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, environment access is gated by the …
    CVE-2026-49860 (CVSS 5.2) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was ope…
    CVE-2026-49859 (CVSS 5.2) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when fetch() was called, Deno check…
    CVE-2026-49440 (CVSS 7.4) — Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrime(candidate[, …

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High