CVE-2025-39817

Advisory lineage Upstream: 0 Downstream: 53
Modified
Published: 16 Sept 2025, 13:00
Last modified:23 May 2026, 16:00

Vulnerability Summary

Overall Risk (default)
medium
28/100
CVSS Score
7.1 HIGH
v3.1 (nvd)
EPSS Score
0.02% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

16 Sept 2025, 13:00
Published
Vulnerability first disclosed
23 May 2026, 16:00
Last Modified
Vulnerability information updated

Description

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 ->d_compare efivarfs_d_compare // oob Fix it by checking 'guid' before cmp.

CVSS Metrics

  • v3.1•HIGH•Score: 7.1CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS Trends

Current EPSS score: 0.02%• Percentile: 6%

Techniques & Countermeasures

  • CWE-125•Out-of-bounds Read

    The product reads data past the end, or before the beginning, of the intended buffer.

Affected Systems

  • debian•debian_linux

    11.0

  • linux•linux

    ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6 | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < 794399019301944fd6d2e0d7a51b3327e26c410e | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < 568e7761279b99c6daa3002290fd6d8047ddb6d2 | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7 | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < 925599eba46045930b850a98ae594d2e3028ac40 | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < c2925cd6207079c3f4d040d082515db78d63afbf | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < 71581a82f38e5a4d807d71fc1bb59aead80ccf95 | ≥ da27a24383b2b10bf6ebd0db29b325548aafecb4, < a6358f8cf64850f3f27857b8ed8c1b08cfc4685c | 688289c4b745c018b3449b4b4c5a2030083c8eaf | ≥ 3.8.2, < 3.9 | 3.9

  • linux•linux_kernel

    ≥ 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:rc1 | 6.17:rc2 | 6.17:rc3

References (11)