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.
References
Configurations
Configuration 1 (hide)
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Configuration 2 (hide)
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History
16 Jan 2026, 20:08
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6 - Patch | |
| References | () https://git.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2 - Patch | |
| References | () https://git.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95 - Patch | |
| References | () https://git.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410e - Patch | |
| References | () https://git.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40 - Patch | |
| References | () https://git.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c - Patch | |
| References | () https://git.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbf - Patch | |
| References | () https://git.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7 - Patch | |
| References | () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html - Third Party Advisory | |
| References | () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html - Third Party Advisory | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.1 |
| CWE | CWE-125 | |
| First Time |
Linux
Debian Debian debian Linux Linux linux Kernel |
|
| CPE | cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* |
03 Nov 2025, 18:16
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
16 Sep 2025, 13:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-09-16 13:15
Updated : 2026-01-16 20:08
NVD link : CVE-2025-39817
Mitre link : CVE-2025-39817
CVE.ORG link : CVE-2025-39817
JSON object : View
Products Affected
debian
- debian_linux
linux
- linux_kernel
CWE
CWE-125
Out-of-bounds Read
