CVE-2025-39817

HIGH EPSS 4.8%

Published Sep 16, 20259mo ago · Modified Jun 17, 20261w ago

7.1 CVSS 3.1

High

Published Sep 16, 2025 9mo ago

Last Modified Jun 17, 2026 1w ago

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 Details

Base Score

7.1

Exploitability

1.8

Impact

5.2

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Attack Vector Local

Attack Complexity Low

Privileges Required Low

User Interaction None

Scope Unchanged

Confidentiality High

Integrity None

Availability High

Threat Intelligence

EPSS Exploit Probability

4.8% percentile

Exploit & Patch Status

No Known Exploit

Patch Available

Weaknesses 1

CWE-125 Out-of-bounds Read Memory Safety

Affected Products 11

Vendor	Product	Version	Range
linux	linux_kernel	*	≥3.8.2 – <5.4.298
linux	linux_kernel	*	≥5.5 – <5.10.242
linux	linux_kernel	*	≥5.11 – <5.15.191
linux	linux_kernel	*	≥5.16 – <6.1.150
linux	linux_kernel	*	≥6.2 – <6.6.104
linux	linux_kernel	*	≥6.7 – <6.12.45
linux	linux_kernel	*	≥6.13 – <6.16.5
linux	linux_kernel	6.17	any
linux	linux_kernel	6.17	any
linux	linux_kernel	6.17	any
debian	debian_linux	11.0	any

References 11

cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-032379.html
git.kernel.org https://git.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6

Patch
git.kernel.org https://git.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2

Patch
git.kernel.org https://git.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95

Patch
git.kernel.org https://git.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410e

Patch
git.kernel.org https://git.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40

Patch
git.kernel.org https://git.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c

Patch
git.kernel.org https://git.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbf

Patch
git.kernel.org https://git.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7

Patch
lists.debian.org https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

Third Party Advisory
lists.debian.org https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html

Third Party Advisory

Remediation

git.kernel.org https://git.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6

Patch
git.kernel.org https://git.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2

Patch
git.kernel.org https://git.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95

Patch
git.kernel.org https://git.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410e

Patch
git.kernel.org https://git.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40

Patch
git.kernel.org https://git.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c

Patch
git.kernel.org https://git.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbf

Patch
git.kernel.org https://git.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7

Patch