CURL-CVE-2020-8284

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    CURL-CVE-2020-8284

    Published: 9 Dec 2020Last Modified: 27 May 2026
    Aliases:

    Summary: trusting FTP PASV responses

    Details: When curl performs a passive FTP transfer, it first tries the `EPSV` command and if that is not supported, it falls back to using `PASV`. Passive mode is what curl uses by default. A server response to a `PASV` command includes the (IPv4) address and port number for the client to connect back to in order to perform the actual data transfer. This is how the FTP protocol is designed to work. A malicious server can use the `PASV` response to trick curl into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions. If curl operates on a URL provided by a user (which by all means is an unwise setup), a user can exploit that and pass in a URL to a malicious FTP server instance without needing any server breach to perform the attack.

    References:

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 4.0
    Fixed -7.74.0

    Affected versions

    7.73.0

    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
    CURL-CVE-2020-8284 | CVE-DB