CVE-2023-6693: qemu Stack Overflow — Fix

Description

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.

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CVSS v3.1 Score

4.9

MEDIUM

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

Weakness Type (CWE)

CWE-121 CWE-121

CWE-787 Out-of-bounds Write

Affected Products

Vendor	Product	Versions
qemu	qemu	< 8.2.1
redhat	enterprise_linux	All
redhat	enterprise_linux	All
redhat	enterprise_linux	All
fedoraproject	fedora	All

References

Advisories & Patches

https://bugzilla.redhat.com/show_bug.cgi?id=2254580 https://bugzilla.redhat.com/show_bug.cgi?id=2254580

Other References

https://access.redhat.com/errata/RHSA-2024:2962 https://access.redhat.com/errata/RHSA-2025:4492 https://access.redhat.com/security/cve/CVE-2023-6693 https://access.redhat.com/errata/RHSA-2024:2962 https://access.redhat.com/security/cve/CVE-2023-6693 https://lists.debian.org/debian-lts-announce/2025/04/msg00042.html https://lists.fedoraproject.org/archives/list/[email protected]/message/OYGUN5HVOXESW7MSNM44E4AE2VNXQB6Y/ https://security.netapp.com/advisory/ntap-20240208-0004/

Frequently Asked Questions

What is CVE-2023-6693? +

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. It has a CVSS v3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2023-6693? +

CVE-2023-6693 has a CVSS v3.1 score of 4.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2023-6693? +

CVE-2023-6693 affects products from fedoraproject, qemu, redhat, specifically: enterprise_linux, fedora, qemu. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2023-6693? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2023-6693