CVE-2021-34557

low-risk
Published 2021-06-10

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.

Do I need to act?

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0.07% chance of exploitation
EPSS score — low exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.6/10 Medium
PHYSICAL / LOW complexity

Affected Products (2)

Xscreensaver

Affected Vendors

Fedoraproject Xscreensaver Project

References (14)

Mailing List http://www.openwall.com/lists/oss-security/2021/06/11/1
Exploit http://www.openwall.com/lists/oss-security/2021/07/06/2
Issue Tracking https://github.com/QubesOS/qubes-issues/issues/6595
Exploit https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txt
Patch https://github.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outp...
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...
Exploit https://www.openwall.com/lists/oss-security/2021/06/05/1
Mailing List http://www.openwall.com/lists/oss-security/2021/06/11/1
Exploit http://www.openwall.com/lists/oss-security/2021/07/06/2
Issue Tracking https://github.com/QubesOS/qubes-issues/issues/6595
Exploit https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txt
Patch https://github.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outp...
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...
Exploit https://www.openwall.com/lists/oss-security/2021/06/05/1
23
/ 100
low-risk
Severity 16/34 · Moderate
Exploitability 0/34 · Minimal
Exposure 7/34 · Low