Bug 2513527

Summary: CVE-2026-6426 qemu: vhost inflight migration VMState integer type mismatch causes out-of-bounds access [fedora-all]
Product: [Fedora] Fedora Reporter: Mauro Matteo Cascella <mcascell>
Component: qemuAssignee: Fedora Virtualization Maintainers <virt-maint>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: low Docs Contact:
Priority: low    
Version: 45CC: berrange, cfergeau, crobinso, mcascell, pbonzini, rjones, suraj.ghimire7, virt-maint
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["91f926a2-6245-45ff-a058-2f5a067e3a5f"]}
Fixed In Version: Doc Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2513498    

Description Mauro Matteo Cascella 2026-08-10 14:30:11 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

A type mismatch vulnerability was found in QEMU's vhost inflight migration VMState handling. The inflight destination buffer size is stored as a uint64_t field, but the VMS_VBUFFER load path reads it as a signed int32_t. On little-endian hosts, a crafted incoming migration state with bit 31 set causes the value to be interpreted as negative, which is then converted to a very large size_t. QEMU may then copy migration-stream data beyond the mmap-backed destination inflight region, resulting in a destination QEMU process crash or memory corruption.

Exploitation requires control of the migration producer or write access to the migration channel, combined with a configuration using vhost inflight migration.

Comment 1 Aoife Moloney 2026-08-17 15:50:43 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 45 development cycle.
Changing version to 45.