CVE-2011-3346 in Red Hat
Summary
by MITRE
Buffer overflow in hw/scsi-disk.c in the SCSI subsystem in QEMU before 0.15.2, as used by Xen, might allow local guest users with permission to access the CD-ROM to cause a denial of service (guest crash) via a crafted SAI READ CAPACITY SCSI command. NOTE: this is only a vulnerability when root has manually modified certain permissions or ACLs.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability identified as CVE-2011-3346 represents a critical buffer overflow condition within the SCSI subsystem of QEMU virtualization software, specifically affecting the hw/scsi-disk.c component. This flaw exists in QEMU versions prior to 0.15.2 and poses significant security risks when utilized within Xen virtualization environments. The vulnerability manifests when local guest users who possess CD-ROM access permissions execute a crafted SAI READ CAPACITY SCSI command, potentially leading to guest system crashes and denial of service conditions. The security implications extend beyond simple disruption as this vulnerability leverages the trust relationship between guest operating systems and virtualized hardware components, creating a pathway for privilege escalation and system instability.
The technical nature of this vulnerability stems from improper input validation within the SCSI command handling mechanism of QEMU's virtual disk subsystem. When processing the SAI READ CAPACITY command, the software fails to properly bounds-check the incoming data buffer, allowing maliciously crafted input to overwrite adjacent memory locations. This buffer overflow condition directly violates CWE-121, which addresses stack-based buffer overflow vulnerabilities, and CWE-122, covering heap-based buffer overflow scenarios. The flaw occurs in the SCSI disk emulation layer where guest operating systems communicate with virtualized storage devices, making it particularly dangerous in virtualized environments where multiple guests share the same host resources. The vulnerability's exploitation requires minimal privileges since it only necessitates access to CD-ROM devices within the guest system, making it accessible to users who would normally have limited system access.
The operational impact of CVE-2011-3346 extends beyond simple denial of service to potentially compromise entire virtualized environments. When exploited, the buffer overflow causes guest virtual machines to crash, leading to service disruption for legitimate users and potential data loss. In Xen environments, where multiple virtual machines share the same physical host, this vulnerability creates a vector for cross-tenant attacks that could affect other guests running on the same hypervisor. The vulnerability's severity is amplified by the fact that it only requires minimal guest-level permissions to exploit, meaning that unprivileged users within a virtual machine could potentially cause system-wide disruptions. This aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, and demonstrates how virtualization environments can introduce unique attack vectors that traditional security models may not adequately address.
The vulnerability's exploitation scenario requires specific environmental conditions, as noted in the original description, since it only becomes exploitable when root has manually modified permissions or ACLs. This modification creates a dangerous situation where guest users gain access to CD-ROM devices with elevated privileges, essentially creating a trusted execution environment that can be leveraged for malicious purposes. The necessity for manual permission changes suggests that system administrators may have inadvertently created security misconfigurations that enable this vulnerability, highlighting the importance of proper access control policies and least privilege principles. Organizations should consider implementing mandatory access controls and regular security audits to prevent such misconfigurations. The vulnerability's remediation requires updating QEMU to version 0.15.2 or later, which includes proper bounds checking and input validation mechanisms. Security practitioners should also implement monitoring solutions to detect anomalous SCSI command sequences and consider network segmentation to limit the potential impact of such vulnerabilities in virtualized environments.