Vulnerability Name:

CVE-2021-34557 (CCN-203671)

Assigned:2021-06-10
Published:2021-06-10
Updated:2021-09-21
Summary: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.
CVSS v3 Severity:4.6 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
4.1 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:U/RC:R)
Exploitability Metrics:Attack Vector (AV): Physical
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
4.6 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
4.1 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:U/RC:R)
Exploitability Metrics:Attack Vector (AV): Physical
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
CVSS v2 Severity:2.1 Low (CVSS v2 Vector: AV:L/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
4.9 Medium (CCN CVSS v2 Vector: AV:L/AC:L/Au:N/C:N/I:N/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Complete
Vulnerability Type:CWE-120
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2021-34557

Source: MLIST
Type: Mailing List, Third Party Advisory
[oss-security] 20210611 Re: XScreenSaver 5.45: Disconnecting a video output can cause XScreenSaver to crash and unlock

Source: MLIST
Type: Exploit, Mailing List, Third Party Advisory
[oss-security] 20210706 xscreensaver 5.45 crash

Source: XF
Type: UNKNOWN
xscreensaver-cve202134557-dos(203671)

Source: MISC
Type: Issue Tracking, Third Party Advisory
https://github.com/QubesOS/qubes-issues/issues/6595

Source: MISC
Type: Exploit, Third Party Advisory
https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txt

Source: MISC
Type: Patch, Third Party Advisory
https://github.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outputs-info.patch

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2021-5af4452ffd

Source: CCN
Type: oss-sec Mailing List, Fri, 11 Jun 2021 09:13:18 +0200
Re: XScreenSaver 5.45: Disconnecting a video output can cause XScreenSaver to crash and unlock

Source: CCN
Type: JWZ Web site
XScreenSaver

Source: MISC
Type: Exploit, Mailing List, Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/06/05/1

Vulnerable Configuration:Configuration 1:
  • cpe:/a:xscreensaver_project:xscreensaver:5.45:*:*:*:*:*:*:*

    • Configuration 2:
  • cpe:/o:fedoraproject:fedora:33:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    Oval Definitions
    Definition IDClassTitleLast Modified
    oval:org.opensuse.security:def:6127
    P
    		Security update for xscreensaver (Moderate)
    2022-08-03
    BACK
    xscreensaver_project xscreensaver 5.45
    fedoraproject fedora 33