Bug 1974194 (CVE-2021-34557) - CVE-2021-34557 XScreenSaver: buffer overflow in update_screen_layout() allows an attacker to bypass the standard screen lock authentication
Summary: CVE-2021-34557 XScreenSaver: buffer overflow in update_screen_layout() allows...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2021-34557
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-06-21 06:27 UTC by Marian Rehak
Modified: 2021-10-28 05:29 UTC (History)
1 user (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2021-10-28 05:29:54 UTC
Embargoed:

Attachments (Terms of Use)

Description Marian Rehak 2021-06-21 06:27:51 UTC 
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.

Reference:

https://github.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outputs-info.patch
https://github.com/QubesOS/qubes-issues/issues/6595
https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txt
https://www.openwall.com/lists/oss-security/2021/06/05/1
http://www.openwall.com/lists/oss-security/2021/06/11/1
Comment 1 Fedora Update System 2021-08-19 01:10:54 UTC 
FEDORA-2021-5af4452ffd has been pushed to the Fedora 33 stable repository.
If problem still persists, please make note of it in this bug report.
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