CVE-2021-34557

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    CVE-2021-34557

    Published: 10 Jun 2021Last Modified: 16 Apr 2026

    Summary:

    Details: XScreenSaver 5.45 can be bypassed if the machine has more than ten disconnectable video outputs. A buffer overflow in update_screen_layout() allows an attacker to bypass the standard screen lock authentication mechanism by crashing XScreenSaver. The attacker must physically disconnect many video outputs.

    References: https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TC4QB7TRS4GS7LDXQQ4PC6J3LVFJYISV/, http://www.openwall.com/lists/oss-security/2021/06/11/1, https://github.com/QubesOS/qubes-issues/issues/6595, https://github.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outputs-info.patch, https://www.openwall.com/lists/oss-security/2021/06/05/1, http://www.openwall.com/lists/oss-security/2021/07/06/2, https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txt

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: N/A

    Events:

    Introduced- None
    Fixed -None

    Affected versions

    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
    CVE-2021-34557 | CVE-DB