Go to homepageCyberStrike

Menu

Star on GitHub · 3.2k
Sign inDownload

CVE-2025-39817

7.1 · HIGH

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-…

Published Sep 16, 2025CWE-125EPSS 0.17%

Overview

CVE-2025-39817 is a high-severity vulnerability. It was published on September 16, 2025 and has a CVSS 3.1 base score of 7.1 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

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

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6Refgit.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2Refgit.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95Refgit.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410eRefgit.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40Refgit.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685cRefgit.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbfRefgit.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7Reflists.debian.org/debian-lts-announce/2025/10/msg00007.htmlReflists.debian.org/debian-lts-announce/2025/10/msg00008.html

How CyberStrike helps

Frequently asked questions

What is CVE-2025-39817?

CVE-2025-39817 is a high-severity vulnerability. It was published on September 16, 2025 and has a CVSS 3.1 base score of 7.1 (HIGH).

How severe is CVE-2025-39817?

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-39817?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-39817?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-39817 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

Related HIGH CVEs from 2025

View all
Browse by year2026202520242023202220212020201920182017201620152014201320122011201020092008200720062005200420032002200120001999