efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare
CVSS score
7.1
EPSS probability
%0.2
Risk score
0.0
Published
1 y ago
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Vulnerability description
DayBreach CVE AI Research
CVE-2025-39817 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.
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.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2025-39817 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
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SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 7.1 | CVSS V31 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H | NVD |
| 7.1 | CVSS V3_1 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H | CVE CNA |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-39817 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-39817 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
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