Linux Kernel up to 6.17-rc3 efivarfs efivarfs_d_compare out-of-bounds

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CTI Interest Score
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4.8$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.17-rc3. Affected is the function efivarfs_d_compare of the component efivarfs. This manipulation causes out-of-bounds. This vulnerability appears as CVE-2025-39817. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel up to 6.17-rc3. Affected by this vulnerability is the function efivarfs_d_compare of the component efivarfs. The manipulation with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2025-39817 since 04/16/2025. The exploitation appears to be difficult. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 265263 (Linux Distros Unpatched Vulnerability : CVE-2025-39817), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.298, 5.10.242, 5.15.191, 6.1.150, 6.6.104, 6.12.45, 6.16.5 or 6.17-rc4 eliminates this vulnerability. Applying the patch 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6/794399019301944fd6d2e0d7a51b3327e26c410e/568e7761279b99c6daa3002290fd6d8047ddb6d2/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7/925599eba46045930b850a98ae594d2e3028ac40/c2925cd6207079c3f4d040d082515db78d63afbf/71581a82f38e5a4d807d71fc1bb59aead80ccf95/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (265263), EUVD (EUVD-2025-29597) and CERT Bund (WID-SEC-2025-2077). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.8

VulDB Base Score: 2.6
VulDB Temp Score: 2.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.1
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
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Nessus ID: 265263
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-39817

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.298/5.10.242/5.15.191/6.1.150/6.6.104/6.12.45/6.16.5/6.17-rc4
Patch: 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6/794399019301944fd6d2e0d7a51b3327e26c410e/568e7761279b99c6daa3002290fd6d8047ddb6d2/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7/925599eba46045930b850a98ae594d2e3028ac40/c2925cd6207079c3f4d040d082515db78d63afbf/71581a82f38e5a4d807d71fc1bb59aead80ccf95/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c

Timelineinfo

04/16/2025 CVE reserved
09/16/2025 +153 days Advisory disclosed
09/16/2025 +0 days VulDB entry created
05/24/2026 +250 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-39817 (🔒)
GCVE (CVE): GCVE-0-2025-39817
GCVE (VulDB): GCVE-100-324433
EUVD: 🔒
CERT Bund: WID-SEC-2025-2077 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 09/16/2025 16:04
Updated: 05/24/2026 19:20
Changes: 09/16/2025 16:04 (59), 09/18/2025 17:28 (2), 10/21/2025 08:55 (7), 12/27/2025 13:43 (1), 01/16/2026 22:33 (11), 05/24/2026 19:20 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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