CVE-2025-39817

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Source
https://cve.org/CVERecord?id=CVE-2025-39817
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39817.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2025-39817
Downstream
Related
Published
2025-09-16T13:00:17.776Z
Modified
2026-03-13T04:06:15.774794Z
Summary
efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare
Details

In the Linux kernel, the following vulnerability has been resolved:

efivarfs: Fix slab-out-of-bounds in efivarfsdcompare

Observed on kernel 6.6 (present on master as well):

BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasancheckrange+0xe8/0x190 __asanloadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfsd_compare+0x68/0xd8 __dlookuprcuopcompare+0x178/0x218 __dlookuprcu+0x1f8/0x228 dallocparallel+0x150/0x648 lookupopen.isra.0+0x5f0/0x8d0 openlastlookups+0x264/0x828 pathopenat+0x130/0x3f8 dofilpopen+0x114/0x248 dosysopenat2+0x340/0x3c0 __arm64sysopenat+0x120/0x1a0

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

T1 T2 lookupopen ->lookup simplelookup 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.

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39817.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
da27a24383b2b10bf6ebd0db29b325548aafecb4
Fixed
0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6
Fixed
794399019301944fd6d2e0d7a51b3327e26c410e
Fixed
568e7761279b99c6daa3002290fd6d8047ddb6d2
Fixed
d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7
Fixed
925599eba46045930b850a98ae594d2e3028ac40
Fixed
c2925cd6207079c3f4d040d082515db78d63afbf
Fixed
71581a82f38e5a4d807d71fc1bb59aead80ccf95
Fixed
a6358f8cf64850f3f27857b8ed8c1b08cfc4685c
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Last affected
688289c4b745c018b3449b4b4c5a2030083c8eaf

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39817.json"