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

CVE-2025-39715 is fixed in linux on 1 platform, first by DEBIAN-CVE-2025-39715, released September 5, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-39715
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 5, 2025
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-39715

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.153-1 | [DEBIAN-CVE-2025-39715](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39715.md) | Sep 5, 2025 |
| Linux | linux Debian 13.5 (trixie) | 6.12.48-1 | [DEBIAN-CVE-2025-39715](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39715.md) | Sep 5, 2025 |
| Linux | linux Debian 14 | 6.16.5-1 | [DEBIAN-CVE-2025-39715](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39715.md) | Sep 5, 2025 |

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