ZephyrProject Zephyr up to 4.4.2 MMU ASID Allocation arch/arm64/core/mmu.c arch_mem_domain_init privileges management

Summaryinfo

A vulnerability described as very critical has been identified in ZephyrProject Zephyr up to 4.4.2. This affects the function arch_mem_domain_init of the file arch/arm64/core/mmu.c of the component MMU ASID Allocation. Such manipulation leads to privileges management. This vulnerability is uniquely identified as CVE-2026-19574. Local access is required to approach this attack. No exploit exists. It is best practice to apply a patch to resolve this issue.

Detailsinfo

A vulnerability was found in ZephyrProject Zephyr up to 4.4.2 and classified as very critical. Affected by this issue is the function arch_mem_domain_init of the file arch/arm64/core/mmu.c of the component MMU ASID Allocation. The manipulation with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

The ARM64 MMU back-end allocated address space identifiers (ASIDs) for memory domains with a bare round-robin counter in arch_mem_domain_init() (arch/arm64/core/mmu.c). VM_ASID_BITS is 8, so only 255 ASIDs exist; once the counter wrapped, arch_mem_domain_init() could hand an ASID to a new domain while a still-live domain held the same one. Domain-private mappings are installed non-global (MT_NG), so the ASID is the only tag separating one domain's cached translations from another's in the TLB. The context-switch path in z_arm64_swap_ptables() only flushes the TLB when the outgoing and incoming domains carry the same ASID, which does not cover a duplicate reached through a third domain: for domains A and C sharing an ASID and an unrelated domain B, the schedule A -> B -> C never takes the flush branch, so the ASID-tagged entries A populated remain resident while C runs. Under SMP two live domains sharing an ASID can additionally be resident on two CPUs at once, which the architecture does not allow for distinct translation-table sets. Triggering the wrap requires a CONFIG_USERSPACE application on ARM64 that creates more than 255 memory domains over its lifetime; k_mem_domain_init() and k_mem_domain_deinit() are supervisor-only APIs and are not exposed as syscalls, so an unprivileged thread cannot drive the counter directly. Once two live domains alias, however, a user-mode thread in one domain can read and write memory belonging to the other domain's partitions and thread stacks with that domain's permissions, defeating the memory-domain isolation boundary. The fix scans the live domain_list before assigning an ASID, advances the round-robin counter past ASIDs already in use, and returns -ENOMEM when all are taken, so domain creation fails closed instead of silently aliasing.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-19574 since 08/11/2026. The exploitation is known to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/09/2026). This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Applying the patch 805054b8ed89dd5441fbca36b3cd3be7e4fb4100 is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• ZephyrProject

Name

• Zephyr

Version

• 4.4.0
• 4.4.1
• 4.4.2

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