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CVE-2021-34557

4.6 · MEDIUM

XScreenSaver 5.45 can be bypassed if the machine has more than ten disconnectable video outputs.

Published Jun 10, 2021CWE-120EPSS 0.48%

Overview

CVE-2021-34557 is a medium-severity vulnerability. It was published on June 10, 2021 and has a CVSS 3.1 base score of 4.6 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.6, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refwww.openwall.com/lists/oss-security/2021/06/11/1Refwww.openwall.com/lists/oss-security/2021/07/06/2GitHubgithub.com/QubesOS/qubes-issues/issues/6595GitHubgithub.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txtGitHubgithub.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outputs-info.patchReflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TC4QB7TRS4GS7LDXQQ4PC6J3LVFJYISV/Refwww.openwall.com/lists/oss-security/2021/06/05/1Refwww.openwall.com/lists/oss-security/2021/06/11/1Refwww.openwall.com/lists/oss-security/2021/07/06/2GitHubgithub.com/QubesOS/qubes-issues/issues/6595

How CyberStrike helps

Frequently asked questions

What is CVE-2021-34557?

CVE-2021-34557 is a medium-severity vulnerability. It was published on June 10, 2021 and has a CVSS 3.1 base score of 4.6 (MEDIUM).

How severe is CVE-2021-34557?

This vulnerability has a CVSS 3.1 base score of 4.6, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-34557?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-34557?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-34557 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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