CVE-2026-3842: Qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host oob write

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-16 · updated 2026-09-01
Weakness: CWE-787

Description

A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpu_physical_memory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in unauthorized access to guest memory or corruption of heap-allocated objects, potentially causing information disclosure, data integrity issues, or a denial of service.

References

https://access.redhat.com/security/cve/CVE-2026-3842
https://bugzilla.redhat.com/show_bug.cgi?id=2458150
https://access.redhat.com/security/cve/CVE-2026-3842
https://bugzilla.redhat.com/show_bug.cgi?id=2458150
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3842.json

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