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CVE-2026-52969 Linux CVE debrief

CVE-2026-52969 is a high-severity vulnerability in the Linux kernel's KVM subsystem. A u64 wrap issue allows for out-of-bounds memory access, enabling local, unprivileged attackers to potentially escalate privileges or crash the system. The vulnerability arises from inadequate validation of the 'offset' variable in the kvm_reset_dirty_gfn() function. An attacker can exploit this by crafting specific entries in the dirty ring buffer, leading to an out-of-bounds load of a kvm_rmap_head structure. This vulnerability affects systems using KVM with a Linux kernel prior to the patched version.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-24
Original CVE updated
2026-06-30
Advisory published
2026-06-24
Advisory updated
2026-06-30

Who should care

System administrators and security teams managing Linux-based virtualization environments using KVM should prioritize patching this vulnerability. The vulnerability's high CVSS score of 7 indicates significant risk, especially in environments where unprivileged users have access to the system. Successful exploitation could lead to privilege escalation or denial-of-service conditions.

Technical summary

The vulnerability is caused by an unchecked addition in the kvm_reset_dirty_gfn() function, which can lead to a u64 wrap-around. This allows an attacker to bypass the bounds check and access memory outside the allocated memslot. The issue is exacerbated by the use of MAP_SHARED for the dirty ring backing, enabling an attacker to modify the slot and offset fields of entries between kernel pushes and KVM_RESET_DIRTY_RINGS consumption. The vulnerability can be exploited from any process holding /dev/kvm, making it a significant concern for virtualized environments.

Defensive priority

High priority should be given to applying patches or mitigations for this vulnerability. Given its high severity and the potential for local privilege escalation or denial-of-service, immediate action is recommended. System administrators should review their KVM and Linux kernel versions, apply available patches, and consider implementing compensating controls to limit the risk until patches can be applied.

Recommended defensive actions

  • Apply the official patches provided by the Linux kernel maintainers to address the u64 wrap vulnerability in KVM.
  • Review and update Linux kernel versions to ensure they include the fix for CVE-2026-52969.
  • Limit access to /dev/kvm to trusted users and groups to reduce the attack surface.
  • Monitor system logs for suspicious activity related to KVM and dirty ring buffer manipulation.
  • Consider implementing additional security controls, such as SELinux or AppArmor policies, to restrict KVM operations.

Evidence notes

The CVE-2026-52969 vulnerability was publicly disclosed on 2026-06-24 with a CVSS score of 7 and HIGH severity. Multiple references are provided, including links to kernel.org and Red Hat's security advisories. The vulnerability affects KVM users with unprivileged access to the system.

Official resources

This article was generated with AI assistance based on the supplied source corpus and is intended for informational purposes only. It provides a debrief on CVE-2026-52969, a vulnerability in the Linux kernel's KVM subsystem. Readers are enc