CVE-2026-53354: Arm TLB Invalidation Memory Ordering Flaw in Linux Kernel

Technical summary

This vulnerability affects Arm CPU implementations where a TLBI;DSB (TLB Invalidate with Data Synchronization Barrier) sequence may complete prematurely, before global observation of memory writes that were translated by the invalidated TLB entry. The errata do not affect TLB entry invalidation itself—entries are removed correctly—but rather the completion semantics of memory operations that used those entries. The mitigation employs ARM64_WORKAROUND_REPEAT_TLBI, which executes a second TLBI;DSB sequence after the first. This double-barrier approach guarantees that memory effects are globally visible before the kernel proceeds. Multiple Arm CPUs share variants of this erratum due to IP reuse in Arm's product portfolio.

Business impact

On affected systems, this memory ordering weakness could allow privileged code or in-kernel exploits to cause data corruption, information disclosure, or denial of service. Because the vulnerability requires local privilege (non-root user execution context) to reach affected code paths, the threat is primarily from container escapes, VM breakouts, or exploitation by already-authenticated users. Organizations running untrusted workloads or multi-tenant environments on Arm64 servers are most at risk. The impact is high—confidentiality, integrity, and availability are all compromised—but exploitability is restricted to local attackers with some privilege.

Affected systems

The Linux kernel on Arm64 (ARM64) systems is the primary affected component. The vulnerability affects specific Arm CPU models that exhibit this TLB invalidation errata; exact models should be identified in the kernel errata documentation and vendor advisories. Both physical servers and virtualized systems running affected Arm processors are in scope. This does not affect x86, PowerPC, or other non-Arm architectures.

Exploitability

Exploitation requires local code execution with user-level privileges (non-root), placing this in a medium-to-high practical risk category. The attacker must trigger the vulnerable TLBI;DSB sequence under conditions where race timing allows memory writes to be observed out of order. This is not trivial—it requires understanding of kernel memory management and careful timing—but is feasible for motivated adversaries with local access. Remote exploitation is not possible. Public exploit code is not known to exist at this time.

Remediation

Apply a patched Linux kernel that includes the ARM64_WORKAROUND_REPEAT_TLBI mitigation enabled for affected CPU models. Kernel versions prior to the fix are vulnerable; verify the specific kernel version containing the patch via your Linux distribution or kernel.org. The mitigation is a software-only change and requires no firmware updates or hardware replacement, though performance impact from the double TLBI;DSB sequence should be negligible on most workloads.

Patch guidance

Obtain and deploy a Linux kernel version that resolves CVE-2025-10263 (note: the description references this related CVE ID) and includes ARM64_WORKAROUND_REPEAT_TLBI enabled by default for affected Arm CPUs. Check your distribution's kernel security advisories for backported patches. If running a long-term support kernel, ensure you receive updates from your vendor or kernel maintainer. Verify that the workaround is active on your systems post-patch by checking kernel logs or errata documentation.

Detection guidance

Patch management is the primary control. Detection of active exploitation is difficult because the vulnerability manifests as subtle memory ordering violations rather than crash signatures. Enable kernel audit logging and monitor for unexpected memory access patterns or corruption in safety-critical data structures. On systems with verbose logging, check dmesg and kernel errata messages to confirm ARM64_WORKAROUND_REPEAT_TLBI is active. Vulnerability scanning should track Linux kernel version against published patch metadata.

Why prioritize this

Assign HIGH priority. The CVSS 8.8 score reflects high impact (confidentiality, integrity, and availability all compromised) on affected systems. Although exploitability requires local privilege, the scope of memory ordering violations—potentially affecting any privileged operation or inter-process communication—is broad. Organizations running multi-tenant Arm64 infrastructure should treat this as urgent. Systems handling sensitive data or running security-critical workloads should be patched immediately. Lower priority may be assigned to single-user or air-gapped Arm64 systems with restricted local access.

Risk score, explained

CVSS 8.8 (HIGH) reflects: Attack Vector Local (user must have local access), Access Complexity Low (no special conditions required once local access is gained), Privileges Required Low (non-root user can trigger), User Interaction None (automatic once conditions are met), and Scope Changed with High impact to Confidentiality, Integrity, and Availability. The score appropriately captures that while the barrier to exploitation is local privilege, the consequences are severe and wide-reaching across system memory safety.

Frequently asked questions