CVE-2021-34557

Exp

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.

Published: 2021-06-10 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-34557 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.17%). 3 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-34557

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-34557

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-01 0.07% 0.17% +0.11%
2 2025-11-21 0.17% 0.07% -0.10%
3 2025-11-18 — 0.17% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34557

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.6 3.1 MEDIUM
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.9 3.6 [email protected]
2.1 2.0 LOW
AV:L/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-2021-34557

OS Trackers for CVE-2021-34557

vendor priority summary link
alpine medium CVE-2021-34557: 1 source package rows (xscreensaver); 7 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2021-34557
debian not yet assigned CVE-2021-34557 not yet assigned priority: Debian including 1 source packages (xscreensaver), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-34557
suse medium CVE-2021-34557 severity moderate: SUSE including 10 source package names (xscreensaver, xscreensaver-5.07-6.37.3.1, …), 17 product×package rows across 7 product lines (SUSE Linux Enterprise Module for Basesystem 15 SP3, SUSE Linux Enterprise Module for Basesystem 15 SP4, … (7 product lines)): Fixed 14, Known Not Affected 3. https://www.suse.com/security/cve/CVE-2021-34557/
ubuntu medium CVE-2021-34557 medium priority: Ubuntu including 1 source packages (xscreensaver), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 6, ignored 4, needs-triage 4, DNE 1, released 1. https://ubuntu.com/security/CVE-2021-34557

Affected software / configurations for CVE-2021-34557

Vendor Product Version Raw CPE
xscreensaver_project xscreensaver 5.45 cpe:2.3:a:xscreensaver_project:xscreensaver:5.45:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

References for CVE-2021-34557

cvelogic Threat Intelligence