CURL-CVE-2021-22925

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    CURL-CVE-2021-22925

    Published: 21 Jul 2021Last Modified: 27 May 2026

    Summary: TELNET stack contents disclosure again

    Details: curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS` in libcurl. This rarely used option is used to send variable=content pairs to TELNET servers. Due to flaw in the option parser for sending `NEW_ENV` variables, libcurl could be made to pass on uninitialized data from a stack based buffer to the server. Therefore potentially revealing sensitive internal information to the server using a clear-text network protocol. This could happen because curl did not call and use `sscanf()` correctly when parsing the string provided by the application. The previous curl security vulnerability [CVE-2021-22898](https://curl.se/docs/CVE-2021-22898.html) is almost identical to this one but the fix was insufficient so this security vulnerability remained.

    References:

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 7.7
    Fixed -7.78.0

    Affected versions

    7.77.0

    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-2021-22925 | CVE-DB