PYSEC-2026-1427

    Dashboard / Vulnerabilities / PYSEC-2026-1427

    PYSEC-2026-1427

    Published: 7 Jul 2026Last Modified: 7 Jul 2026

    Summary: Connection confusion in gRPC

    Details: When gRPC HTTP2 stack raised a header size exceeded error, it skipped parsing the rest of the HPACK frame. This caused any HPACK table mutations to also be skipped, resulting in a desynchronization of HPACK tables between sender and receiver. If leveraged, say, between a proxy and a backend, this could lead to requests from the proxy being interpreted as containing headers from different proxy clients - leading to an information leak that can be used for privilege escalation or data exfiltration.

    References: https://nvd.nist.gov/vuln/detail/CVE-2023-32731, https://github.com/grpc/grpc/issues/33463, https://github.com/grpc/grpc/pull/32309, https://github.com/grpc/grpc/pull/33005, https://github.com/grpc/grpc/commit/29d8beee0ac2555773b2a2dda5601c74a95d6c10, https://github.com/grpc/grpc/commit/65a2a895afaf1d2072447b9baf246374b182a946, https://github.com/grpc/grpc/releases/tag/v1.53.1, https://github.com/grpc/grpc/releases/tag/v1.54.2, https://github.com/rubysec/ruby-advisory-db/blob/master/gems/grpc/CVE-2023-32731.yml, https://pypi.org/project/grpcio, https://github.com/advisories/GHSA-cfgp-2977-2fmm

    Affected packages

    Package

    Name: grpcio

    Purl: pkg:pypi/grpcio

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 1.53.0
    Fixed -1.53.1

    Affected versions

    1.53.0

    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
    PYSEC-2026-1427 | CVE-DB