CVE-2024-25743 Overview
CVE-2024-25743 is a high-severity vulnerability affecting the Linux kernel through version 6.9. The flaw allows an untrusted hypervisor to inject virtual interrupts 0 and 14 at any point in time, which can trigger the SIGFPE signal handler in userspace applications. This vulnerability specifically impacts systems using AMD Secure Encrypted Virtualization with Secure Nested Paging (SEV-SNP) and AMD Secure Encrypted Virtualization with Encrypted State (SEV-ES) technologies.
Critical Impact
An untrusted hypervisor can manipulate guest VM execution by injecting arbitrary virtual interrupts, potentially disrupting confidential computing workloads and undermining the security guarantees of AMD SEV technologies.
Affected Products
- Linux kernel through version 6.9
- Systems utilizing AMD SEV-SNP (Secure Encrypted Virtualization - Secure Nested Paging)
- Systems utilizing AMD SEV-ES (Secure Encrypted Virtualization - Encrypted State)
Discovery Timeline
- 2024-05-15 - CVE-2024-25743 published to NVD
- 2025-03-14 - Last updated in NVD database
Technical Details for CVE-2024-25743
Vulnerability Analysis
This vulnerability represents an improper input validation issue (CWE-20) within the Linux kernel's handling of virtual interrupts in AMD SEV-SNP and SEV-ES environments. AMD's SEV technologies are designed to protect virtual machines from a potentially malicious hypervisor by encrypting guest memory and CPU state. However, this vulnerability undermines these protections by allowing the hypervisor to inject specific virtual interrupts that should not be controllable by untrusted code.
The vulnerability requires local access to exploit, meaning an attacker would need to control the hypervisor environment. When exploited, an untrusted hypervisor can inject interrupt 0 (divide-by-zero exception) and interrupt 14 (page fault exception) into a guest VM at arbitrary times. This injection capability allows the hypervisor to trigger unexpected SIGFPE signal handlers in userspace applications running within the protected guest, potentially leading to information disclosure or integrity violations.
Root Cause
The root cause of CVE-2024-25743 lies in insufficient validation of virtual interrupt sources within the Linux kernel's AMD SEV interrupt handling code. The kernel fails to properly verify that certain interrupts are genuine hardware exceptions rather than maliciously injected events from an untrusted hypervisor. Interrupts 0 and 14 should only be generated by actual CPU exceptions (division errors and page faults respectively), but the lack of origin validation allows the hypervisor to synthesize these interrupts and deliver them to the guest OS.
Attack Vector
The attack vector for this vulnerability is local, requiring the attacker to control the hypervisor hosting the target virtual machine. In cloud computing environments where confidential computing with AMD SEV is deployed, this would typically require a compromised or malicious cloud provider infrastructure. The attacker exploits the vulnerability by:
- Identifying a guest VM protected by AMD SEV-SNP or SEV-ES
- Crafting and injecting virtual interrupt 0 or 14 into the guest at a chosen moment
- Causing the guest kernel to deliver a SIGFPE signal to userspace applications
- Observing application behavior or exploiting signal handler side effects to compromise confidentiality or integrity
The attack does not require user interaction and can be executed with low privileges from the hypervisor context. The vulnerability primarily impacts confidentiality and integrity without directly affecting availability.
Detection Methods for CVE-2024-25743
Indicators of Compromise
- Unexpected SIGFPE signals in applications that do not perform division operations
- Anomalous interrupt patterns in guest VM logs, particularly interrupts 0 and 14 occurring without corresponding CPU exceptions
- Application crashes or unexpected signal handler invocations in SEV-protected VMs
Detection Strategies
- Monitor for unusual SIGFPE signal delivery patterns in confidential computing workloads
- Implement kernel-level logging to track interrupt injection events in SEV-protected guests
- Review system logs for applications unexpectedly entering signal handlers without arithmetic operations
- Deploy runtime integrity monitoring to detect anomalous interrupt behavior
Monitoring Recommendations
- Enable enhanced logging for AMD SEV guest environments to capture interrupt delivery events
- Implement alerting for applications that receive unexpected SIGFPE signals
- Periodically audit kernel versions across confidential computing infrastructure to ensure patched versions are deployed
- Monitor vendor security bulletins including AMD Security Bulletin SB-3008 for updates
How to Mitigate CVE-2024-25743
Immediate Actions Required
- Update Linux kernel to a patched version that addresses CVE-2024-25743
- Review AMD SEV-SNP and SEV-ES deployments for exposure to this vulnerability
- Consult AMD Security Bulletin SB-3008 for vendor-specific guidance
- Assess the trust model of your hypervisor environment, particularly in multi-tenant cloud scenarios
Patch Information
Security patches addressing this vulnerability are being tracked by major Linux distributions. For detailed patch information and status, refer to the following vendor resources:
Organizations should apply kernel updates from their respective Linux distribution vendors as they become available.
Workarounds
- Consider temporarily avoiding AMD SEV-SNP/SEV-ES for highly sensitive workloads until patches are applied
- Implement application-level hardening to handle unexpected signals gracefully
- Deploy workloads only on trusted hypervisor infrastructure where the risk of malicious interrupt injection is minimized
- Monitor applications for unexpected signal handler behavior and implement defensive coding practices in signal handlers
Organizations should prioritize kernel patching as the primary remediation strategy, as workarounds do not fully address the underlying vulnerability.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
