Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: riscv: Fix register corruption from uninitialized cregs on error… (CVE-2026-64082)

The vulnerability (CVE-2026-64082) in the Linux kernel's RISC-V architecture involves the functions compat_riscv_gpr_set() and compat_restore_sigcontext() calling cregs_to_regs() unconditionally, even when user memory copy operations fail. Because cregs is an uninitialized stack variable, failure in user_regset_copyin() or __copy_from_user() leads to uninitialized stack data being written into the target task's pt_regs, corrupting its register state and potentially leaking kernel stack contents. The fix ensures cregs_to_regs() is only called when the user copy succeeds, preventing register corruption and information leakage. This vulnerability has been addressed in multiple Linux kernel releases, with patches available.

Successful exploitation can lead to corruption of the register state of kernel tasks and signal-returning tasks, potentially leaking kernel stack contents. This can compromise system integrity and confidentiality by exposing sensitive kernel memory data and destabilizing task execution. The CVSS score of 7.8 indicates a high impact on confidentiality, integrity, and availability, requiring local privileges with low complexity and no user interaction.

A patch is available and should be applied promptly. The vendor advisory from Ubuntu confirms that the issue has been fixed in updated Linux kernel packages. Users should update their systems to the fixed kernel versions listed in the advisory and reboot to apply the changes. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be necessary. No additional mitigation steps are required beyond applying the official fix.