CVE-2025-37846: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-37846 is a vulnerability discovered in the Linux kernel's ARM64 MOPS (Memory Operations) implementation, identified on May 9, 2025. The vulnerability affects the source register handling during SET operations in the Linux kernel, specifically when the MOPS exception is taken from a SET* sequence with XZR (register 31) as the source (NVD CVE, Wiz Security).

The vulnerability stems from an improper source register dereference during SET operations in the ARM64 MOPS implementation. The source register is not used for SET operations, but reading it can result in a UBSAN out-of-bounds array access error. This occurs specifically when the MOPS exception is taken from a SET sequence with XZR (register 31) as the source. Architecturally, this represents the only case where a src/dst/size field in the ESR can be reported as 31. Prior to the fix (commit 2de451a329cf662b), the code in doel0mops() was benign as the use of ptregsread_reg() prevented the out-of-bounds access. The vulnerability has been assigned a CVSS v3.1 base score of 5.5 (Red Hat Security).

The vulnerability has been classified with a moderate severity rating, primarily affecting newer versions of Linux distributions. The impact is limited to systems running affected versions of the Linux kernel with ARM64 architecture (Red Hat Security).

Red Hat has deferred the fix for Red Hat Enterprise Linux 9 and kernel-rt packages, while versions 6, 7, and 8 are not affected by this vulnerability. Ubuntu has marked this vulnerability as 'work in progress' for newer releases (25.04 plucky, 24.10 oracular, and 24.04 LTS noble), while older LTS releases (22.04, 20.04, 18.04, and 16.04) are not affected (Red Hat Security, Ubuntu Security).