CVE-2021-3507

What it is

A heap buffer overflow was found in the floppy disk emulator of QEMU up to 6.0.0 (including). It could occur in fdctrl_transfer_handler() in hw/block/fdc.c while processing DMA read data transfers from the floppy drive to the guest system. A privileged guest user could use this flaw to crash the QEMU process on the host resulting in DoS scenario, or potential information leakage from the host memory.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2021-05-06 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:05 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 6.1 MEDIUM (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2021-05-06 16:15 UTC

Last modified

2026-06-17 04:05 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-119 · Buffer errors

Record status

Modified

Affected

• Qemu ≤ 6.0.0
• Debian Linux 10.0
• Redhat Enterprise Linux 8.0

Attack profile CVSS 3.1 · 6.1

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-3507.md and follow it. Check whether this project is affected by CVE-2021-3507. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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