In the Linux kernel, the following vulnerability has been resolved: mm/rmap: fix missing barrier between anon_vma init and vma->anon_vma publish On… (CVE-2026-98507)

The vulnerability involves a missing memory barrier in the Linux kernel's anon_vma initialization and publication process within __anon_vma_prepare(). On arm64 servers, concurrent faults on adjacent VMAs that are anon_vma-compatible but not merged can cause two threads to race when preparing anon_vma structures. Due to store reordering and insufficient memory ordering guarantees, one thread may observe stale anon_vma->root pointers, leading to use-after-free conditions. This results in locking and unlocking different anon_vma->root structures, causing one anon_vma to never be unlocked and another to become permanently locked. The issue manifests as hung tasks waiting indefinitely on anon_vma locks.

Tasks on affected arm64 Linux kernels may become indefinitely blocked (hung tasks) due to deadlocks in anon_vma locking caused by use-after-free and inconsistent lock states. This can degrade system stability and responsiveness, particularly under concurrent memory faults on adjacent VMAs.

A fix for this vulnerability has been implemented in the Linux kernel. Users should update to a kernel version that includes this patch. Since no specific patched versions are provided, check the official Linux kernel advisories or vendor updates for the fixed version. Until patched, avoid workloads that cause concurrent faults on adjacent VMAs or apply kernel-level mitigations if available.