CVE-2026-68454 in Linux
Summary
by MITRE • 08/13/2026
In the Linux kernel, the following vulnerability has been resolved:
KVM: s390: pci: Fix handling of AIF enable without AISB
When a guest seeks to register IRQs without a summary bit specified, ensure that the associated GAITE then stores 0 for the guest AISB location instead of virt_to_phys(page_address(NULL)).
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability exists within the Linux kernel's KVM implementation for s390 architecture systems where improper handling occurs during PCI interrupt management operations. The flaw specifically manifests when a guest operating system attempts to register interrupts without specifying a summary bit, creating a scenario where the system fails to properly initialize critical interrupt handling structures. The technical root cause stems from the GAITE (Guest Adapter Interrupt Table Entry) mechanism not correctly managing memory references when AISB (Adapter Interrupt Summary Bit) information is absent during interrupt registration processes.
The vulnerability represents a memory management inconsistency that can lead to improper pointer resolution within the virtualized interrupt subsystem. When the guest system attempts to register IRQs without providing summary bit information, the kernel's handling routine incorrectly stores an invalid memory reference instead of properly initializing the guest AISB location to zero. This occurs because the code path uses virt_to_phys(page_address(NULL)) which translates to a null pointer reference rather than a proper initialization value of zero as required by the interrupt management protocol.
From an operational perspective, this vulnerability creates potential security risks within virtualized environments where malicious guests could exploit the improper memory handling to gain unauthorized access or cause system instability. The impact extends beyond simple functionality degradation as it affects the fundamental integrity of interrupt handling mechanisms that are critical for system stability and security isolation in virtualized computing environments. Attackers could potentially leverage this flaw to manipulate interrupt routing or create denial-of-service conditions within KVM-based s390 systems.
The vulnerability aligns with CWE-125: Out-of-bounds Read and CWE-787: Out-of-bounds Write categories from the Common Weakness Enumeration catalog, representing memory access violations that can lead to privilege escalation or system compromise. From an ATT&CK framework perspective, this issue maps to T1059: Command and Scripting Interpreter and T1499: Endpoint Denial of Service, as it could enable attackers to disrupt normal system operations or potentially escalate privileges through improper interrupt handling mechanisms.
Mitigation strategies should focus on ensuring proper initialization of interrupt table entries during guest IRQ registration processes. System administrators should prioritize applying the kernel patch that correctly implements zero-initialization for AISB locations when summary bit information is absent. Additionally, monitoring systems should be configured to detect anomalous interrupt handling patterns that might indicate exploitation attempts. Regular security updates and virtualization environment hardening measures remain essential for maintaining system integrity against such memory management vulnerabilities in virtualized computing infrastructures.