Medium [CVE-2026-6426] vhost inflight migration VMState integer type mismatch causes out-of-bounds access
This medium-severity Red Hat Linux advisory covers CVE-2026-6426 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
A type mismatch vulnerability was found in QEMU's vhost inflight migration VMState handling. The destination buffer size is stored as a uint64_t but read by the VMS_VBUFFER load path 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 and then implicitly converted to a very large size_t, leading qemu_get_buffer() to copy migration-stream data beyond the bounds of the mmap-backed inflight region. This can result in a crash of the QEMU process or memory corruption.
Exploitation requires control of the migration producer or write access to the migration channel, combined with a destination configured to use vhost inflight migration. Red Hat severity: Low — CVSS 4.4 (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-681. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux for NVIDIA 26; Red Hat OpenShift Container Platform 4.
Will not fix / out of support: Red Hat Enterprise Linux for NVIDIA 26. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: qemu-kvm-ma.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 26 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 26 days ago·verify at source
Mitigation checklist
- If vhost inflight migration is not required, it can be disabled by omitting the inflight parameter from the vhost-user device configuration. This prevents the vulnerable VMState deserialization path from being reached on the destination. Environments that require vhost inflight migration for live migration of vhost-user devices cannot use this mitigation and should prioritize applying the fix.
Official advisory · high-confidence parse· fetched 26 days ago·verify at source
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