GHSA-6v7p-g79w-8964

    Dashboard / Vulnerabilities / GHSA-6v7p-g79w-8964

    GHSA-6v7p-g79w-8964

    Published: 19 Jun 2026Last Modified: 10 Sept 2026

    Summary: MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error

    Details: ### Impact If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. If the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack. ### Patches v1.2.1 ### Workarounds Users should create a new Unpacker instead of reusing the same Unpacker after an error occurs. Applying the above patch can prevent SEGV, but reusing the Streaming Unpacker after it has encountered an error will not yield correct data. If an error occurs during Streaming Unpacking, the Stream and Streaming Unpacker should be discarded. Therefore, this is not just a workaround but the correct solution. The above patch only prevents crashes from incorrect usage.

    References: https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964, https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d, https://github.com/msgpack/msgpack-python, https://github.com/msgpack/msgpack-python/releases/tag/v1.2.1

    Affected packages

    Package

    Name: msgpack

    Purl: pkg:pypi/msgpack

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -1.2.1

    Affected versions

    0.5.0
    0.5.1
    0.5.2
    0.5.3
    0.5.4
    0.5.5
    0.5.6

    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-6v7p-g79w-8964 | CVE-DB