CVE-2021-3527
Publication date 26 May 2021
Last updated 18 August 2025
Ubuntu priority
Description
A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper validation. Since the total size is not bounded, a malicious guest could use this flaw to influence the array length and cause the QEMU process to perform an excessive allocation on the stack, resulting in a denial of service.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| qemu | 25.10 questing |
Fixed 1:6.0+dfsg-2expubuntu1
|
| 25.04 plucky |
Fixed 1:6.0+dfsg-2expubuntu1
|
|
| 24.04 LTS noble |
Fixed 1:6.0+dfsg-2expubuntu1
|
|
| 22.04 LTS jammy |
Fixed 1:6.0+dfsg-2expubuntu1
|
|
| 20.04 LTS focal |
Fixed 1:4.2-3ubuntu6.17
|
|
| 18.04 LTS bionic |
Fixed 1:2.11+dfsg-1ubuntu7.37
|
|
| 16.04 LTS xenial |
Vulnerable
|
|
| 14.04 LTS trusty |
Vulnerable
|
|
| qemu-kvm | 25.10 questing | Not in release |
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release |
Patch details
| Package | Patch details |
|---|---|
| qemu |
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
5.5 · Medium
|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
References
Related Ubuntu Security Notices (USN)
- USN-5010-1
- QEMU vulnerabilities
- 15 July 2021