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Linux Kernel CVE-2025-38396

HIGH
2025-07-25 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Authentication Bypass Linux Debian Red Hat Debian Linux Suse
7.8
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
4.4 MEDIUM

Local low-priv process invoking memfd_secret bypasses LSM/SELinux policy on secretmem - a limited confidentiality/integrity enforcement gap, no availability impact, making the official C:H/I:H/A:H look inflated.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
6.0 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jul 30, 2026 - 08:24 vuln.today
CVE Published
Jul 25, 2025 - 13:15 nvd
HIGH 7.8

DescriptionNVD

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

fs: export anon_inode_make_secure_inode() and fix secretmem LSM bypass

Export anon_inode_make_secure_inode() to allow KVM guest_memfd to create anonymous inodes with proper security context. This replaces the current pattern of calling alloc_anon_inode() followed by inode_init_security_anon() for creating security context manually.

This change also fixes a security regression in secretmem where the S_PRIVATE flag was not cleared after alloc_anon_inode(), causing LSM/SELinux checks to be bypassed for secretmem file descriptors.

As guest_memfd currently resides in the KVM module, we need to export this symbol for use outside the core kernel. In the future, guest_memfd might be moved to core-mm, at which point the symbols no longer would have to be exported. When/if that happens is still unclear.

AnalysisAI

Local privilege/security-policy bypass in the Linux kernel's secretmem subsystem allows LSM and SELinux access controls to be evaded on secretmem file descriptors because the S_PRIVATE flag was left set after alloc_anon_inode(), causing inode_init_security_anon() checks to be skipped. The affected code paths are the anonymous-inode helpers used by secretmem (memfd_secret) and KVM guest_memfd, present in Linux 6.16 release candidates and a Debian backport. There is no public exploit identified and EPSS is very low (0.16%), so the practical impact is a defense-in-depth regression that lets a local process create secretmem objects that mandatory-access-control policy should have denied.

Technical ContextAI

The root cause is in the kernel's anonymous inode creation for security-sensitive memory objects. secretmem (created via the memfd_secret syscall) and KVM's guest_memfd both need anonymous inodes that carry a proper LSM security context. The previous pattern called alloc_anon_inode() and then manually called inode_init_security_anon(); however, alloc_anon_inode() sets the S_PRIVATE inode flag, and when that flag is not cleared the LSM framework treats the inode as internal and skips security initialization/labeling. As a result SELinux (or any LSM) hooks that would evaluate policy for creating these descriptors are bypassed. The fix exports and routes callers through anon_inode_make_secure_inode(), which properly establishes the security context and clears S_PRIVATE so LSM checks run. The CPE data scopes this to cpe:2.3:o:linux:linux_kernel (notably 6.16 rc1-rc4) and cpe:2.3:o:debian:debian_linux:11.0. The NVD lists CWE as N/A; the behavior class is best described as improper enforcement / missing authorization check (CWE-862-style) rather than the 'Authentication Bypass' tag applied in the intel feed.

RemediationAI

Patch available per vendor: apply the upstream stable-tree fixes referenced by NVD (commits 66d29d757c96, 6ca45ea48530, cbe4134ea4bc, e3eed0134772, and f94c422157f3 at git.kernel.org/stable) by updating to the corrected 6.16 build or a distribution kernel that includes them; the exact released tag is not independently confirmed from the input, so treat these as commit-level fixes and pull the vendor's patched package. Debian users should update per the Debian LTS advisory at https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html. If immediate patching is not possible, the practical compensating control is to restrict the memfd_secret capability - e.g. disable secretmem at boot with the kernel command-line parameter secretmem.enable=0 where supported, which removes the vulnerable object type entirely at the cost of losing secretmem functionality - and limit local unprivileged code execution on sensitive hosts. Note that on kernels relying on SELinux/LSM policy to gate secretmem, that policy cannot be trusted to enforce until the patch is applied, so tightening local access controls is the more reliable interim measure.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
Container suse/hpc/warewulf4-x86_64/sle-hpc-node:15.6.17.8.103 Image SLES15-SP6 Image SLES15-SP6-BYOS Image SLES15-SP6-BYOS-Azure Image SLES15-SP6-BYOS-EC2 Image SLES15-SP6-BYOS-GCE Image SLES15-SP6-CHOST-BYOS Image SLES15-SP6-CHOST-BYOS-Aliyun Image SLES15-SP6-CHOST-BYOS-Azure Image SLES15-SP6-CHOST-BYOS-EC2 Image SLES15-SP6-CHOST-BYOS-GCE Image SLES15-SP6-CHOST-BYOS-GDC Image SLES15-SP6-CHOST-BYOS-SAP-CCloud Image SLES15-SP6-EC2 Image SLES15-SP6-EC2-ECS-HVM Image SLES15-SP6-GCE Image SLES15-SP6-HPC-BYOS Image SLES15-SP6-HPC-BYOS-Azure Image SLES15-SP6-HPC-BYOS-EC2 Image SLES15-SP6-HPC-BYOS-GCE Image SLES15-SP6-HPC-EC2 Image SLES15-SP6-HPC-GCE Image SLES15-SP6-Hardened-BYOS Image SLES15-SP6-Hardened-BYOS-Azure Image SLES15-SP6-Hardened-BYOS-EC2 Image SLES15-SP6-Hardened-BYOS-GCE Image SLES15-SP6-SAP Image SLES15-SP6-SAP-Azure Image SLES15-SP6-SAP-EC2 Image SLES15-SP6-SAP-GCE Image SLES15-SP6-SAPCAL Image SLES15-SP6-SAPCAL-Azure Image SLES15-SP6-SAPCAL-EC2 Image SLES15-SP6-SAPCAL-GCE Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.44 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.27 Image SL-Micro Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.67 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.29 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.76 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.14 Affected
Image SLES-Azure-3P Image SLES-Azure-Basic Image SLES-Azure-Standard Image SLES-BYOS-Azure Image SLES-BYOS-EC2 Image SLES-BYOS-GCE Image SLES-CHOST-BYOS-Aliyun Image SLES-CHOST-BYOS-Azure Image SLES-CHOST-BYOS-EC2 Image SLES-CHOST-BYOS-GCE Image SLES-CHOST-BYOS-GDC Image SLES-CHOST-BYOS-SAP-CCloud Image SLES-EC2 Image SLES-EC2-ECS Image SLES-GCE Image SLES-GCE-3P Image SLES-Hardened-BYOS-Azure Image SLES-Hardened-BYOS-EC2 Image SLES-Hardened-BYOS-GCE Image SLES-SAPCAL-Azure Image SLES-SAPCAL-EC2 Image SLES-SAPCAL-GCE Affected

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CVE-2025-38396 vulnerability details – vuln.today
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