CURL-CVE-2019-5481

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    CURL-CVE-2019-5481

    Published: 11 Sept 2019Last Modified: 27 May 2026
    Aliases:

    Summary: FTP-KRB double free

    Details: libcurl can be told to use kerberos over FTP to a server, as set with the `CURLOPT_KRBLEVEL` option. During such kerberos FTP data transfer, the server sends data to curl in blocks with the 32-bit size of each block first and then that amount of data immediately following. A malicious or broken server can claim to send a large block and if by doing that it makes curl's subsequent call to `realloc()` to fail, curl would then misbehave in the exit path and double free the memory. In practical terms, an up to 4 GB memory area may well be fine to allocate on a modern 64-bit system but on 32-bit systems it fails. Kerberos FTP is a rarely used protocol with curl. Also, Kerberos authentication is usually only attempted and used with servers that the client has a previous association with.

    References:

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 7.52.0
    Fixed -7.66.0

    Affected versions

    7.65.3
    7.65.2
    7.65.1
    7.65.0

    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