CVE-2021-3592

An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw exists in the bootp_input() function and could occur while processing a udp packet that is smaller than the size of the 'bootp_t' structure. A malicious guest could use this flaw to leak 10 bytes of uninitialized heap memory from the host. The highest threat from this vulnerability is to data confidentiality. This flaw affects libslirp versions prior to 4.6.0.

Published: 2021-06-15 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3592 is rated Low Risk (16.7/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.02%). Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

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

Exploit prediction scoring system (EPSS) score for CVE-2021-3592

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 2025-11-21 0.07% 0.02% -0.04%
2 2025-11-18 0.05% 0.07% +0.02%
3 2023-03-07 — 0.05% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3592

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.8 3.1 LOW
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.0 1.4 [email protected]
2.1 2.0 LOW
AV:L/AC:L/Au:N/C:P/I:N/A:N 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:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-2021-3592

OS Trackers for CVE-2021-3592

vendor priority summary link
alpine low CVE-2021-3592: 1 source package rows (libslirp); 13 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 6. https://security.alpinelinux.org/vuln/CVE-2021-3592
debian not yet assigned CVE-2021-3592 not yet assigned priority: Debian including 2 source packages (libslirp, qemu), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 10. https://security-tracker.debian.org/tracker/CVE-2021-3592
gentoo low CVE-2021-3592: 1 GLSA(s) (202107-44), 1 atom(s) (net-libs/libslirp); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-3592
redhat low — https://access.redhat.com/security/cve/CVE-2021-3592
suse low CVE-2021-3592 severity low: SUSE including 510 source package names (0.49.0.16.7:libslirp0-4.3.1-150300.2.7.1, 0.49.0.18.8:libslirp0-4.3.1-150300.2.7.1, …), 1092 product×package rows across 75 product lines (Container rancher/elemental-teal-iso/5.4, Container rancher/elemental-teal-rt/5.4, … (75 product lines)): Fixed 763, Known Affected 225, Known Not Affected 104. https://www.suse.com/security/cve/CVE-2021-3592/
ubuntu low CVE-2021-3592 low priority: Ubuntu including 2 source packages (libslirp, qemu), 28 status rows across 14 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): released 13, not-affected 10, DNE 2, needs-triage 2, ignored 1. https://ubuntu.com/security/CVE-2021-3592

Affected software / configurations for CVE-2021-3592

Vendor Product Version Raw CPE
libslirp_project libslirp < 4.6.0 cpe:2.3:a:libslirp_project:libslirp:*:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

References for CVE-2021-3592

cvelogic Threat Intelligence