#VU58812 Off-by-one in QEMU - CVE-2021-3930

Vulnerability identifier: #VU58812

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-3930

CWE-ID: CWE-193

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
QEMU
Client/Desktop applications / Virtualization software

Vendor: QEMU

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

The vulnerability exists due to an off-by-one error in the SCSI device emulation in QEMU. A remote user on the guest OS can can trigger an off-by-one error while processing MODE SELECT commands in mode_sense_page() if the 'page' argument is set to MODE_PAGE_ALLS (0x3f). Successful exploitation of the vulnerability may result in QEMU crash.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

QEMU: 6.0.0 - 6.1.0

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=2020588
https://gitlab.com/qemu-project/qemu/-/commit/b3af7fdf9cc537f8f0dd3e2423d83f5c99a457e8
https://www.mail-archive.com/qemu-devel@nongnu.org/msg779652.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.