CVE-2023-6693 | Qemu: virtio-net: stack buffer overflow in virtio_net_flush_tx()

A stack based buffer overflow was found in the virtio-net device of QEMU. This issue occurs when flushing TX in the virtio_net_flush_tx function if guest features VIRTIO_NET_F_HASH_REPORT, VIRTIO_F_VERSION_1 and VIRTIO_NET_F_MRG_RXBUF are enabled. This could allow a malicious user to overwrite local variables allocated on the stack. Specifically, the `out_sg` variable could be used to read a part of process memory and send it to the wire, causing an information leak.

Published: 2024-01-02 Last update: 2025-11-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-6693 is rated Low Risk (21.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2023-6693

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% 0.03% -0.04%
2 2025-11-18 0.03% 0.07% +0.04%
3 2025-03-30 — 0.03% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-6693

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.9 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.4 3.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L 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:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.8 3.4 [email protected]

Weakness enumeration for CVE-2023-6693

OS Trackers for CVE-2023-6693

vendor priority summary link
alpine — CVE-2023-6693: 1 source package rows (qemu); 1 state rows across 1 repos (3.19-community); fixed 0, open 1. https://security.alpinelinux.org/vuln/CVE-2023-6693
debian not yet assigned CVE-2023-6693 not yet assigned priority: Debian including 1 source packages (qemu), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-6693
redhat medium — https://access.redhat.com/security/cve/CVE-2023-6693
suse medium CVE-2023-6693 severity moderate: SUSE including 707 source package names (2.0.2-2.2.85:qemu-guest-agent-7.1.0-150500.49.12.1, amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, …), 882 product×package rows across 27 product lines (Container suse/sle-micro/kvm-5.5, Image SLES12-SP5-EC2-ECS-On-Demand, … (27 product lines)): Fixed 567, Known Affected 231, Known Not Affected 84. https://www.suse.com/security/cve/CVE-2023-6693/
ubuntu medium CVE-2023-6693 medium priority: Ubuntu including 1 source packages (qemu), 9 status rows across 9 suites (bionic, focal, jammy, lunar, mantic, noble, trusty, upstream, xenial): not-affected 5, ignored 2, released 2. https://ubuntu.com/security/CVE-2023-6693

Affected software / configurations for CVE-2023-6693

Vendor Product Version Raw CPE
qemu qemu < 8.2.1 cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*
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:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
fedoraproject fedora 39 cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*

References for CVE-2023-6693

cvelogic Threat Intelligence