SB2026081686 - Use of Uninitialized Variable in Linux kernel s390 kvm

Description

This security bulletin contains information about 1 vulnerability.

1) Use of Uninitialized Variable (CVE-ID: CVE-2026-72292)

CWE-ID: CWE-457 - Use of Uninitialized Variable

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to disclose sensitive information.

The vulnerability exists due to uninitialized memory in kvm_s390_get_cmma_bits() when handling KVM_S390_GET_CMMA_BITS requests on the non-peek migration path. A local user can invoke the affected operation to disclose sensitive information.

Only pages with the CMMA dirty bit set have their output bytes written, while clean and unmapped pages within the reported span can leave gaps that are copied to user space.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/a4a19941ccb2164edc3491faa5ac5df82e94b363
• https://git.kernel.org/stable/c/c7dda3d0f869dc97223448a06c9a2e5235928e48