CVE-2026-58846 in Android
Summary
by MITRE • 09/09/2026
In kvm_iommu_map_sg of iommu.c, there is a possible use after free due to a missing permission check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified in the kvm_iommu_map_sg function within the iommu.c module represents a critical security flaw rooted in insufficient access control mechanisms during memory mapping operations involving scatter-gather lists. This specific implementation error allows an attacker to exploit a use-after-free condition by bypassing necessary permission checks that are intended to validate whether the requesting entity has authorized rights to map physical addresses into the guest's address space through the IOMMU subsystem. The absence of these validation steps creates a scenario where memory regions can be manipulated or accessed after they have been freed, leading to undefined behavior and potential control over system execution flow.
From a technical perspective, this flaw falls under CWE-416, which classifies use-after-free vulnerabilities as situations where pointers are used after their associated memory has been deallocated. In the context of KVM (Kernel-based Virtual Machine), the IOMMU subsystem is responsible for translating device DMA addresses to physical host addresses and enforcing isolation between virtual machines. When kvm_iommu_map_sg processes a scatter-gather list, it must ensure that all pages involved are valid and accessible according to strict security policies. The missing permission check means that an unprivileged user or a compromised guest VM can trigger this function with maliciously crafted inputs, causing the kernel to reference memory structures that have already been released back to the allocator. This dereference of freed memory allows for arbitrary read/write primitives depending on how quickly the memory is reallocated by other system processes.
The operational impact of this vulnerability is severe, primarily due to its potential for local privilege escalation. An attacker who gains access to a user-level account or a less-privileged virtual machine can exploit this flaw to execute code with kernel privileges effectively bypassing isolation boundaries. Since no additional execution privileges are required and user interaction is not needed, the attack vector is straightforward and highly exploitable in multi-tenant environments where multiple users share underlying hardware resources through virtualization layers. The lack of user interaction requirement significantly lowers the barrier for exploitation, making it a high-risk issue that can lead to complete compromise of the host system integrity.
This vulnerability aligns with MITRE ATT&CK techniques related to privilege escalation and defense evasion, specifically those involving kernel exploitation or memory corruption attacks such as T1068 Exploitation for Privilege Escalation. The ability to escalate privileges from a low-privilege context to root level without authentication highlights the critical nature of proper input validation in hypervisor components. Attackers can leverage this flaw to establish persistence, exfiltrate sensitive data stored on the host, or pivot to other systems within the network by gaining full control over the virtualization infrastructure.
Mitigation strategies must focus on implementing rigorous permission checks before any IOMMU mapping operations are executed. Developers should ensure that kvm_iommu_map_sg validates user permissions and verifies the validity of all memory pages in the scatter-gather list prior to proceeding with the mapping process. Additionally, employing static analysis tools and fuzzing techniques during development can help identify similar logic errors across other kernel modules. System administrators should apply vendor-provided patches promptly as they become available, which typically include fixes for these specific access control gaps. Regular auditing of hypervisor configurations and monitoring for anomalous memory allocation patterns can also provide early detection indicators for potential exploitation attempts in production environments.