FKIE_CVE-2025-39817
Vulnerability from fkie_nvd - Published: 2025-09-16 13:15 - Updated: 2026-01-16 20:08
Severity ?
Summary
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
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| debian | debian_linux | 11.0 |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nefivarfs: Fix slab-out-of-bounds in efivarfs_d_compare\n\nObserved on kernel 6.6 (present on master as well):\n\n BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0\n Call trace:\n kasan_check_range+0xe8/0x190\n __asan_loadN+0x1c/0x28\n memcmp+0x98/0xd0\n efivarfs_d_compare+0x68/0xd8\n __d_lookup_rcu_op_compare+0x178/0x218\n __d_lookup_rcu+0x1f8/0x228\n d_alloc_parallel+0x150/0x648\n lookup_open.isra.0+0x5f0/0x8d0\n open_last_lookups+0x264/0x828\n path_openat+0x130/0x3f8\n do_filp_open+0x114/0x248\n do_sys_openat2+0x340/0x3c0\n __arm64_sys_openat+0x120/0x1a0\n\nIf dentry-\u003ed_name.len \u003c EFI_VARIABLE_GUID_LEN , \u0027guid\u0027 can become\nnegative, leadings to oob. The issue can be triggered by parallel\nlookups using invalid filename:\n\n T1\t\t\tT2\n lookup_open\n -\u003elookup\n simple_lookup\n d_add\n // invalid dentry is added to hash list\n\n\t\t\tlookup_open\n\t\t\t d_alloc_parallel\n\t\t\t __d_lookup_rcu\n\t\t\t __d_lookup_rcu_op_compare\n\t\t\t hlist_bl_for_each_entry_rcu\n\t\t\t // invalid dentry can be retrieved\n\t\t\t -\u003ed_compare\n\t\t\t efivarfs_d_compare\n\t\t\t // oob\n\nFix it by checking \u0027guid\u0027 before cmp."
}
],
"id": "CVE-2025-39817",
"lastModified": "2026-01-16T20:08:25.680",
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"baseScore": 7.1,
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"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
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"source": "nvd@nist.gov",
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"published": "2025-09-16T13:15:57.187",
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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