GHSA-mrq3-vjjr-p77c

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    GHSA-mrq3-vjjr-p77c

    Published: 2 Feb 2026Last Modified: 4 Feb 2026

    Summary: Fastify Vulnerable to DoS via Unbounded Memory Allocation in sendWebStream

    Details: ### Impact A Denial of Service vulnerability in Fastify’s Web Streams response handling can allow a remote client to exhaust server memory. Applications that return a `ReadableStream` (or `Response` with a Web Stream body) via `reply.send()` are impacted. A slow or non-reading client can trigger unbounded buffering when backpressure is ignored, leading to process crashes or severe degradation. ### Patches The issue is fixed in Fastify 5.7.3. Users should upgrade to 5.7.3 or later. ### Workarounds Avoid sending Web Streams from Fastify responses (e.g., `ReadableStream` or `Response` bodies). Use Node.js streams (`stream.Readable`) or buffered payloads instead until the project can upgrade. ### References - https://hackerone.com/reports/3524779

    Affected packages

    Package

    Name: fastify

    Purl: pkg:npm/fastify

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 0
    Fixed -5.7.3

    Affected versions

    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
    GHSA-mrq3-vjjr-p77c | CVE-DB