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Linux Kernel CVE-2025-38477

MEDIUM
Race Condition (CWE-362)
2025-07-28 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information Disclosure Linux Race Condition Debian Debian Linux
4.7
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
SUSE
MEDIUM
qualitative
Red Hat
7.3 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

2
Analysis Generated
May 12, 2026 - 13:33 vuln.today
CVE Published
Jul 28, 2025 - 12:15 nvd
MEDIUM 4.7

DescriptionNVD

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

net/sched: sch_qfq: Fix race condition on qfq_aggregate

A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free.

This patch addresses the issue by:

  1. Moved qfq_destroy_class into the critical section.
  2. Added sch_tree_lock protection to qfq_dump_class and

qfq_dump_class_stats.

AnalysisAI

A race condition in the Linux kernel's net/sched sch_qfq module allows local authenticated attackers to cause denial of service through NULL pointer dereference or use-after-free errors when concurrent threads modify queue aggregation structures during packet scheduling. The vulnerability requires low privileges and has a low real-world exploitation probability (EPSS 0.02%), though a vendor patch is available.

Technical ContextAI

The vulnerability exists in the QFQ (Quick Fair Queueing) packet scheduler subsystem within the Linux kernel's traffic control (qdisc) framework. QFQ maintains aggregation structures (agg) that group traffic classes for fair bandwidth allocation. The race condition occurs in net/sched/sch_qfq.c when the qfq_change_agg function modifies aggregation metadata during qfq_enqueue operations while concurrent threads-such as qfq_dump_class (used for statistics retrieval) or qfq_delete_class (used for class deletion)-access the same structures without proper synchronization. This is a classic CWE-362 race condition where multiple execution paths access shared mutable state without atomic protection. The fix adds sch_tree_lock critical sections around both data modification and reads, ensuring that qfq_dump_class and qfq_dump_class_stats cannot race against aggregation structure updates.

RemediationAI

Apply the vendor-released kernel security patches available through multiple upstream commits in the stable kernel repository (commits 466e10194ab81caa2ee6a332d33ba16bcceeeba6, 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64, a6d735100f602c830c16d69fb6d780eebd8c9ae1, aa7a22c4d678bf649fd3a1d27debec583414d, c000a3a330d97f6c073ace5aa5faf94b9adb4b79, c6df794000147a3a02f79984aada4ce83f8d0a1e, d841aa5518508ab195b6781ad0d73ee378d713dd, and fbe48f06e64134dfeafa89ad23387f66ebca3527). For Debian and Debian-LTS users, install the patched kernel version referenced in the Debian LTS security advisories (debian-lts-announce 2025/10/msg00007 and 00008). If immediate patching is not feasible, the high attack complexity and local-access requirement mean that restricting local shell access and removing non-root users from systems with QFQ scheduling enabled reduces exposure, though this is a compensating control with significant operational overhead. Upgrading to patched stable kernel releases (6.16 final or later stable branch updates) is the primary recommended action.

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
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
Container suse/sle-micro-rancher/5.2:latest Image SLES15-SP3-Micro-5-2-BYOS-Azure Affected
Container suse/sle-micro-rancher/5.3:latest Container suse/sle-micro-rancher/5.4:5.4.4.5.41 Image SLES15-SP4-BYOS Image SLES15-SP4-BYOS-Azure Image SLES15-SP4-BYOS-EC2 Image SLES15-SP4-BYOS-GCE Image SLES15-SP4-CHOST-BYOS Image SLES15-SP4-CHOST-BYOS-Aliyun Image SLES15-SP4-CHOST-BYOS-Azure Image SLES15-SP4-CHOST-BYOS-EC2 Image SLES15-SP4-CHOST-BYOS-GCE Image SLES15-SP4-CHOST-BYOS-SAP-CCloud Image SLES15-SP4-HPC-BYOS Image SLES15-SP4-HPC-BYOS-Azure Image SLES15-SP4-HPC-BYOS-EC2 Image SLES15-SP4-HPC-BYOS-GCE Image SLES15-SP4-HPC-EC2 Image SLES15-SP4-HPC-GCE Image SLES15-SP4-Hardened-BYOS Image SLES15-SP4-Hardened-BYOS-Azure Image SLES15-SP4-Hardened-BYOS-EC2 Image SLES15-SP4-Hardened-BYOS-GCE Image SLES15-SP4-Manager-Proxy-4-3-BYOS Image SLES15-SP4-Manager-Proxy-4-3-BYOS-Azure Image SLES15-SP4-Manager-Proxy-4-3-BYOS-EC2 Image SLES15-SP4-Manager-Proxy-4-3-BYOS-GCE Image SLES15-SP4-Manager-Server-4-3-BYOS Image SLES15-SP4-Manager-Server-4-3-BYOS-Azure Image SLES15-SP4-Manager-Server-4-3-BYOS-EC2 Image SLES15-SP4-Manager-Server-4-3-BYOS-GCE Image SLES15-SP4-Micro-5-3 Image SLES15-SP4-Micro-5-3-BYOS Image SLES15-SP4-Micro-5-3-BYOS-Azure Image SLES15-SP4-Micro-5-3-BYOS-EC2 Image SLES15-SP4-Micro-5-3-BYOS-GCE Image SLES15-SP4-Micro-5-3-EC2 Image SLES15-SP4-Micro-5-4 Image SLES15-SP4-Micro-5-4-BYOS Image SLES15-SP4-Micro-5-4-BYOS-Azure Image SLES15-SP4-Micro-5-4-BYOS-EC2 Image SLES15-SP4-Micro-5-4-BYOS-GCE Image SLES15-SP4-Micro-5-4-EC2 Image SLES15-SP4-Micro-5-4-GCE Image SLES15-SP4-SAP Image SLES15-SP4-SAP-Azure Image SLES15-SP4-SAP-EC2 Image SLES15-SP4-SAP-GCE Image SLES15-SP4-SAPCAL Image SLES15-SP4-SAPCAL-Azure Image SLES15-SP4-SAPCAL-EC2 Image SLES15-SP4-SAPCAL-GCE Affected

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CVE-2025-38477 vulnerability details – vuln.today
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