CVE-2025-39716: parisc: Revise __get_user() to probe user read access

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-05 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: parisc: Revise __get_user() to probe user read access Because of the way read access support is implemented, read access interruptions are only triggered at privilege levels 2 and 3. The kernel executes at privilege level 0, so __get_user() never triggers a read access interruption (code 26). Thus, it is currently possible for user code to access a read protected address via a system call. Fix this by probing read access rights at privilege level 3 (PRIV_USER) and setting __gu_err to -EFAULT (-14) if access isn't allowed. Note the cmpiclr instruction does a 32-bit compare because COND macro doesn't work inside asm.

Affected products

Debian Linux: 11.0
Linux kernel: from 2.6.13 before 6.1.149; from 6.2 before 6.6.103; from 6.7 before 6.12.44; from 6.13 before 6.16.4; 2.6.12, 2.6.12-rc2, 2.6.12-rc3, 2.6.12-rc4, 2.6.12-rc5 — fixed in 6.1.149, 6.12.44, 6.16.4, 6.6.103

How to fix

Upgrade to a fixed version: Linux kernel 6.1.149, 6.12.44, 6.16.4, 6.6.103. Check the vendor advisory for mitigations.

References

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