CVE-2025-39817 Affecting kernel-rt-64k-modules-partner package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

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  • Snyk IDSNYK-CENTOS9-KERNELRT64KMODULESPARTNER-12837137
  • published17 Sept 2025
  • disclosed16 Sept 2025

Introduced: 16 Sep 2025

NewCVE-2025-39817  (opens in a new tab)

How to fix?

There is no fixed version for Centos:9 kernel-rt-64k-modules-partner.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-modules-partner package and not the kernel-rt-64k-modules-partner package as distributed by Centos. See How to fix? for Centos:9 relevant fixed versions and status.

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

If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename:

T1 T2 lookup_open ->lookup simple_lookup d_add // invalid dentry is added to hash list

        lookup_open
         d_alloc_parallel
          __d_lookup_rcu
           __d_lookup_rcu_op_compare
            hlist_bl_for_each_entry_rcu
            // invalid dentry can be retrieved
             -&gt;d_compare
              efivarfs_d_compare
              // oob

Fix it by checking 'guid' before cmp.

CVSS Base Scores

version 3.1