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Linux CVE-2021-47646

HIGH
Use After Free (CWE-416)
2025-02-26 416baaa9-dc9f-4396-8d5f-8c081fb06d67
7.8
CVSS 3.1 · Vendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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Severity by source

Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67) PRIMARY
7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SUSE
HIGH
qualitative
Red Hat
5.5 MEDIUM
qualitative

Primary rating from Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67).

CVSS VectorVendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

Lifecycle Timeline

3
Analysis Generated
Mar 28, 2026 - 18:28 vuln.today
Patch released
Mar 28, 2026 - 18:28 nvd
Patch available
CVE Published
Feb 26, 2025 - 06:37 nvd
HIGH 7.8

DescriptionCVE.org

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

Revert "Revert "block, bfq: honor already-setup queue merges""

A crash [1] happened to be triggered in conjunction with commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges"). The latter was then reverted by commit ebc69e897e17 ("Revert "block, bfq: honor already-setup queue merges""). Yet, the reverted commit was not the one introducing the bug. In fact, it actually triggered a UAF introduced by a different commit, and now fixed by commit d29bd41428cf ("block, bfq: reset last_bfqq_created on group change").

So, there is no point in keeping commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges") out. This commit restores it.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=214503

AnalysisAI

In the Linux kernel, the following vulnerability has been resolved: Revert "Revert "block, bfq: honor already-setup queue merges"" A crash [1] happened to be triggered in conjunction with commit. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.

Technical ContextAI

This vulnerability is classified as Use After Free (CWE-416), which allows attackers to access freed memory to execute arbitrary code or crash the application. In the Linux kernel, the following vulnerability has been resolved: Revert "Revert "block, bfq: honor already-setup queue merges"" A crash [1] happened to be triggered in conjunction with commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges"). The latter was then reverted by commit ebc69e897e17 ("Revert "block, bfq: honor already-setup queue merges""). Yet, the reverted commit was not the one introducing the bug. In fact, it actually triggered a UAF introduced by a different commit, and now fixed by commit d29bd41428cf ("block, bfq: reset last_bfqq_created on group change"). So, there is no point in keeping commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges") out. This commit restores it. [1] https://bugzilla.kernel.org/show_bug.cgi?id=214503 Affected products include: Linux Linux Kernel.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Use smart pointers or garbage-collected languages. Set pointers to NULL after freeing. Enable memory sanitizers.

Vendor StatusVendor

SUSE

Severity: High
Product Status
Container suse/sle-micro-rancher/5.3:latest Container suse/sle-micro-rancher/5.4:latest 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
Container suse/sle-micro/base-5.5:2.0.4-5.8.160 Image SLES15-SP5-BYOS-Azure Image SLES15-SP5-BYOS-EC2 Image SLES15-SP5-BYOS-GCE Image SLES15-SP5-CHOST-BYOS-Aliyun Image SLES15-SP5-CHOST-BYOS-Azure Image SLES15-SP5-CHOST-BYOS-EC2 Image SLES15-SP5-CHOST-BYOS-GCE Image SLES15-SP5-CHOST-BYOS-GDC Image SLES15-SP5-CHOST-BYOS-SAP-CCloud Image SLES15-SP5-EC2 Image SLES15-SP5-GCE Image SLES15-SP5-HPC-BYOS-Azure Image SLES15-SP5-HPC-BYOS-EC2 Image SLES15-SP5-HPC-BYOS-GCE Image SLES15-SP5-Hardened-BYOS-Azure Image SLES15-SP5-Hardened-BYOS-EC2 Image SLES15-SP5-Hardened-BYOS-GCE Image SLES15-SP5-Manager-Proxy-5-0-BYOS Image SLES15-SP5-Manager-Proxy-5-0-BYOS-Azure Image SLES15-SP5-Manager-Proxy-5-0-BYOS-EC2 Image SLES15-SP5-Manager-Proxy-5-0-BYOS-GCE Image SLES15-SP5-Manager-Server-5-0 Image SLES15-SP5-Manager-Server-5-0-Azure-llc Image SLES15-SP5-Manager-Server-5-0-Azure-ltd Image SLES15-SP5-Manager-Server-5-0-BYOS Image SLES15-SP5-Manager-Server-5-0-BYOS-Azure Image SLES15-SP5-Manager-Server-5-0-BYOS-EC2 Image SLES15-SP5-Manager-Server-5-0-BYOS-GCE Image SLES15-SP5-Manager-Server-5-0-EC2-llc Image SLES15-SP5-Manager-Server-5-0-EC2-ltd Image SLES15-SP5-Micro-5-5 Image SLES15-SP5-Micro-5-5-Azure Image SLES15-SP5-Micro-5-5-BYOS Image SLES15-SP5-Micro-5-5-BYOS-Azure Image SLES15-SP5-Micro-5-5-BYOS-EC2 Image SLES15-SP5-Micro-5-5-BYOS-GCE Image SLES15-SP5-Micro-5-5-EC2 Image SLES15-SP5-Micro-5-5-GCE Image SLES15-SP5-SAPCAL-Azure Image SLES15-SP5-SAPCAL-EC2 Image SLES15-SP5-SAPCAL-GCE Affected
Container suse/sle-micro/kvm-5.5:2.0.4-3.5.304 Affected
Container suse/sle-micro/rt-5.5:2.0.4-4.5.352 Affected
Image SLES15-SP4-SAP-Azure-LI-BYOS Image SLES15-SP4-SAP-Azure-LI-BYOS-Production Image SLES15-SP4-SAP-Azure-VLI-BYOS Image SLES15-SP4-SAP-Azure-VLI-BYOS-Production Image SLES15-SP4-SAP-BYOS Image SLES15-SP4-SAP-BYOS-Azure Image SLES15-SP4-SAP-BYOS-EC2 Image SLES15-SP4-SAP-BYOS-GCE Image SLES15-SP4-SAP-Hardened Image SLES15-SP4-SAP-Hardened-Azure Image SLES15-SP4-SAP-Hardened-BYOS Image SLES15-SP4-SAP-Hardened-BYOS-Azure Image SLES15-SP4-SAP-Hardened-BYOS-EC2 Image SLES15-SP4-SAP-Hardened-BYOS-GCE Image SLES15-SP4-SAP-Hardened-GCE Affected

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CVE-2021-47646 vulnerability details – vuln.today

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