Buffer overflow in Xscreensaver Project
CVE-2021-34557
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.6 (Medium). Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Xscreensaver Project — versions 5.45
- Fedoraproject Fedora — versions 33
Weakness classification (CWE)
References
- github.com/QubesOS/qubes-issues/issues/6595 (Third Party Advisory, Issue Tracking)
- www.openwall.com/lists/oss-security/2021/06/05/1 (Exploit, Mailing List, Third Party Advisory)
- github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-068-2021.txt (Exploit, Third Party Advisory)
- github.com/QubesOS/qubes-xscreensaver/blob/master/0001-Fix-updating-outputs-inf… (Patch, Third Party Advisory)
- www.openwall.com/lists/oss-security/2021/06/11/1 (mailing-list, Mailing List, Third Party Advisory)
- www.openwall.com/lists/oss-security/2021/07/06/2 (mailing-list, Exploit, Mailing List, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2021-34557?
- CVE-2021-34557 is a medium-severity vulnerability in Xscreensaver Project, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 4.6/10. Published 2021-06-10.
- How severe is CVE-2021-34557?
- Medium severity. CVSS v3 base score is 4.6 out of 10.