CVE-2025-61553 in BitVisor
Summary
by MITRE • 10/16/2025
An out-of-bounds write in VirtIO network device emulation in BitVisor from commit 108df6 (2020-05-20) to commit 480907 (2025-07-06) allows local attackers to cause a denial of service (host hypervisor crash) via a crafted PCI configuration space access. Given it's a heap overflow in a privileged hypervisor context, exploitation may enable arbitrary code execution or guest-to-host privilege escalation.
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Analysis
by VulDB Data Team • 10/17/2025
The vulnerability CVE-2025-61553 represents a critical out-of-bounds write flaw in the VirtIO network device emulation component of BitVisor hypervisor. This vulnerability exists within the hypervisor's PCI configuration space handling mechanism, specifically affecting the network device emulation layer that operates in a privileged context. The flaw was introduced between commit 108df6 dated 2020-05-20 and commit 480907 from 2025-07-06, indicating a long-standing issue that has remained unpatched for over five years. The vulnerability manifests when local attackers perform crafted PCI configuration space accesses that trigger memory corruption in the hypervisor's heap management system.
The technical nature of this vulnerability stems from improper bounds checking within the VirtIO network device emulation code that handles PCI configuration space operations. When a maliciously crafted access occurs, the hypervisor fails to validate the bounds of memory operations, leading to an out-of-bounds write condition that can overwrite adjacent memory locations. This heap overflow condition directly impacts the hypervisor's memory management structures, causing unpredictable behavior that ultimately results in a host hypervisor crash. The vulnerability's classification as CWE-787 (Out-of-bounds Write) reflects the fundamental flaw in input validation and memory boundary checking that allows attackers to write beyond allocated memory regions.
The operational impact of CVE-2025-61553 extends beyond simple denial of service, as it represents a significant privilege escalation vector within virtualized environments. Local attackers with access to the hypervisor can leverage this vulnerability to cause host system crashes, potentially leading to complete system compromise. The privilege escalation aspect arises from the fact that the vulnerability exists within a privileged hypervisor context where the attacker can execute code with elevated privileges. This creates a severe threat model where a local user could potentially gain arbitrary code execution capabilities, effectively breaking the isolation guarantees that hypervisors are designed to maintain between guest operating systems and the host system. The vulnerability directly maps to ATT&CK technique T1059.001 (Command and Scripting Interpreter) and T1068 (Exploitation for Privilege Escalation) within the MITRE ATT&CK framework.
Mitigation strategies for CVE-2025-61553 require immediate patching of the BitVisor hypervisor to address the specific memory boundary violations in the VirtIO network device emulation code. Organizations should implement network segmentation and access controls to limit local user privileges within virtualized environments, reducing the attack surface for potential exploitation. Additionally, hypervisor monitoring systems should be deployed to detect anomalous PCI configuration space access patterns that may indicate exploitation attempts. The vulnerability highlights the importance of regular security audits and code reviews, particularly for privileged system components where memory safety issues can have catastrophic consequences. System administrators should also consider implementing hypervisor hardening measures such as disabling unnecessary network device emulation features and maintaining strict access controls to hypervisor management interfaces. The remediation process should include thorough testing to ensure that the patch does not introduce regressions in network functionality while maintaining the security improvements necessary to prevent exploitation of this critical vulnerability.