GO-2026-6617

    Dashboard / Vulnerabilities / GO-2026-6617

    GO-2026-6617

    Published: 8 Oct 2026Last Modified: 8 Oct 2026

    Summary: HTTP/2 server crash due to HPACK encoder race in net/http

    Details: HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently. This happens because the server modifies the HPACK encoder from two goroutines without synchronization: one uses the encoder to encode a HEADERS frame as part of a response sent to a client and the other modifies the encoder's table size when handling a SETTINGS frame containing SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can repeatedly send a request while changing the header table size to crash the server.

    References: https://go.dev/cl/847188, https://go.dev/cl/847313, https://go.dev/issue/81867, https://groups.google.com/g/golang-announce/c/U2fTuyDJznI, https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs

    Affected packages

    Package

    Name: stdlib

    Purl: pkg:golang/stdlib

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 0
    Fixed -1.26.9

    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