CVE-2023-50247

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    CVE-2023-50247

    Published: 12 Dec 2023Last Modified: 28 Oct 2026

    Summary: h2o QUIC state exhaustion DoS

    Details: h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The QUIC stack (quicly), as used by H2O up to commit 43f86e5 (in version 2.3.0-beta and prior), is susceptible to a state exhaustion attack. When H2O is serving HTTP/3, a remote attacker can exploit this vulnerability to progressively increase the memory retained by the QUIC stack. This can eventually cause H2O to abort due to memory exhaustion. The vulnerability has been resolved in commit d67e81d03be12a9d53dc8271af6530f40164cd35. HTTP/1 and HTTP/2 are not affected by this vulnerability as they do not use QUIC. Administrators looking to mitigate this issue without upgrading can disable HTTP/3 support.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/50xxx/CVE-2023-50247.json, https://github.com/h2o/h2o/security/advisories/GHSA-2ch5-p59c-7mv6, https://nvd.nist.gov/vuln/detail/CVE-2023-50247, https://github.com/h2o/h2o/commit/d67e81d03be12a9d53dc8271af6530f40164cd35

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    2.3.0-beta1
    2.3.0-beta2

    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
    CVE-2023-50247 | CVE-DB