CVE-2025-39817 remediation guide

Linux Linux, SIMATIC CN 4100, linux kernel

In the Linux kernel, the following vulnerability has been resolved: efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare Observed on kernel 6.6 (present on master as well): BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasan_check_range+0xe8/0x190 __asan_loadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfs_d_compare+0x68/0xd8 __d_lookup_rcu_op_compare+0x178/0x218 __d_lookup_rcu+0x1f8/0x228 d_alloc_parallel+0x150/0x648 lookup_open.isra.0+0x5f0/0x8d0 open_last_lookups+0x264/0x828 path_openat+0x130/0x3f8 do_filp_open+0x114/0x248 do_sys_openat2+0x340/0x3c0 __arm64_sys_openat+0x120/0x1a0...

Open CVE record

ProductLinux Linux, SIMATIC CN 4100, linux kernel

Affected versions>= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 794399019301944fd6d2e0d7a51b3327e26c410e, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 568e7761279b99c6daa3002290fd6d8047ddb6d2, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 925599eba46045930b850a98ae594d2e3028ac40, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < c2925cd6207079c3f4d040d082515db78d63afbf, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 71581a82f38e5a4d807d71fc1bb59aead80ccf95, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < a6358f8cf64850f3f27857b8ed8c1b08cfc4685c, >= 688289c4b745c018b3449b4b4c5a2030083c8eaf, >= 3.8.2 < 3.9, >= 3.9, < V5.0, >= 3.8.2 < 5.4.298, >= 5.5 < 5.10.242, >= 5.11 < 5.15.191, >= 5.16 < 6.1.150, >= 6.2 < 6.6.104, >= 6.7 < 6.12.45, >= 6.13 < 6.16.5, 6.17

Fixed versions5.4.298, 5.10.242, 5.15.191, 6.1.150, 6.6.104, 6.12.45, 6.16.5

Priority basisReview · CVSS 7.1 · EPSS 0.15%

Identify the affected asset

Confirm whether Linux Linux, SIMATIC CN 4100, linux kernel 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: >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 794399019301944fd6d2e0d7a51b3327e26c410e, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 568e7761279b99c6daa3002290fd6d8047ddb6d2, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 925599eba46045930b850a98ae594d2e3028ac40, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < c2925cd6207079c3f4d040d082515db78d63afbf, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < 71581a82f38e5a4d807d71fc1bb59aead80ccf95, >= da27a24383b2b10bf6ebd0db29b325548aafecb4 < a6358f8cf64850f3f27857b8ed8c1b08cfc4685c, >= 688289c4b745c018b3449b4b4c5a2030083c8eaf, >= 3.8.2 < 3.9, >= 3.9, < V5.0, >= 3.8.2 < 5.4.298, >= 5.5 < 5.10.242, >= 5.11 < 5.15.191, >= 5.16 < 6.1.150, >= 6.2 < 6.6.104, >= 6.7 < 6.12.45, >= 6.13 < 6.16.5, 6.17. 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: 5.4.298, 5.10.242, 5.15.191, 6.1.150, 6.6.104, 6.12.45, 6.16.5. 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.