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CVE-2021-3593

17
FAUCET Score

CVE-2021-3593 describes an invalid pointer initialization vulnerability in the SLiRP networking implementation of QEMU, specifically within the udp6_input() function. This flaw, affecting libslirp versions prior to 4.6.0, can lead to out-of-bounds read access or indirect host memory disclosure when processing undersized UDP packets. The vulnerability is rated as LOW severity (CVSS 3.8), indicating a local attack vector with low complexity, primarily impacting data confidentiality. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.6.0CPE matchmatch criteria
cpe:2.3:a:libslirp_project:libslirp:*:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

3.8LOW

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.0
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.33%
Probability of exploitation in next 30 days
EPSS Percentile
25.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0033 is in the 75th percentile among its peer group of 1,511 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

redhatpatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: virt-devel:rhel-8050020211001230723.b4937e53
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: virt:rhel-8050020211001230723.b4937e53
View patch
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: container-tools:3.0/libslirp
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: container-tools:rhel8/libslirp
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8 Advanced VirtualizationFixed in: virt:8.2/qemu-kvm
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8 Advanced VirtualizationFixed in: virt:8.3/qemu-kvm
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 8 Advanced VirtualizationFixed in: virt:av/qemu-kvm
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: qemu-kvm

Vendor Advisories (1)

redhatCVE-2021-3593Low

QEMU: slirp: invalid pointer initialization may lead to information disclosure (udp6)

Jun 14, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchThird Party Advisory
lists.debian.org / debian-lts-announce/2022/04/msg00002.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2023/03/msg00013.html
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/GCKWZWY64EHTOQMLVLTSZ4AA27EWRJMH
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/SGPQZFVJCFGDSISFXPCQTTBBD7QZLJKI
security.gentoo.org / glsa/202107-44
Third Party Advisory
security.netapp.com / advisory/ntap-20210805-0004
Third Party Advisory