CVE-2025-39881 remediation guide
Linux Linux, linux kernel, debian linux
In the Linux kernel, the following vulnerability has been resolved: kernfs: Fix UAF in polling when open file is released A use-after-free (UAF) vulnerability was identified in the PSI (Pressure Stall Information) monitoring mechanism: BUG: KASAN: slab-use-after-free in psi_trigger_poll+0x3c/0x140 Read of size 8 at addr ffff3de3d50bd308 by task systemd/1 psi_trigger_poll+0x3c/0x140 cgroup_pressure_poll+0x70/0xa0 cgroup_file_poll+0x8c/0x100 kernfs_fop_poll+0x11c/0x1c0 ep_item_poll.isra.0+0x188/0x2c0 Allocated by task 1: cgroup_file_open+0x88/0x388 kernfs_fop_open+0x73c/0xaf0 do_dentry_open+0...
Identify the affected asset
Confirm whether Linux Linux, linux kernel, debian linux is installed, record the deployed version and installation path, and identify exposed interfaces.
- Record the product name, package or appliance identifier, and installed version.
- Identify internet-facing, administrative, API, and internal access paths.
- Preserve the pre-change configuration and relevant service logs.
Validate the affected-version match
Compare the deployed version with the affected range: >= 34f26a15611afb03c33df6819359d36f5b382589 < 34d9cafd469c69ad85e6a36b4303c78382cf5c79, >= 34f26a15611afb03c33df6819359d36f5b382589 < 854baafc00c433cccbe0ab4231b77aeb9b637b77, >= 34f26a15611afb03c33df6819359d36f5b382589 < 7e64474aba78d240f7804f48f2d454dcca78b15f, >= 34f26a15611afb03c33df6819359d36f5b382589 < ac5cda4fae8818cf1963317bb699f7f2f85b60af, >= 34f26a15611afb03c33df6819359d36f5b382589 < 3c9ba2777d6c86025e1ba4186dc5cd930e40ec5f, >= 6.1, >= 6.1 < 6.1.153, >= 6.2 < 6.6.107, >= 6.7 < 6.12.48, >= 6.13 < 6.16.8, 6.17, 11.0. Treat incomplete inventory results as unresolved.
Prioritize with independent signals
The CVSS severity warrants an early asset and exposure review. Combine this signal with asset criticality, exposure, compensating controls, and business impact.
Apply supported remediation
Follow the vendor advisory or supported update path. Current fixed-version status: 6.1.153, 6.6.107, 6.12.48, 6.16.8. Preserve configuration and rollback material before change.
Verify the result
Confirm the resulting version, service health, authentication and access paths, monitoring coverage, and relevant security logs.
- Confirm the expected version and package state.
- Run a functional health check for critical service paths.
- Review authentication, error, application, and security monitoring logs.
- Reassess exposure if the supported fix cannot be applied.
Operational boundary
This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.