Critical Linux Kernel RT Security Update: Patch CVE-2025-21702, 37752, 37797 Immediately

 

Critical openSUSE Linux Kernel RT security update patches 3 zero-day vulnerabilities (CVE-2025-21702, CVE-2025-37752, CVE-2025-37797). Learn patch instructions for SLE 12-SP5, Leap 15.3/15.5, and enterprise systems. Secure your infrastructure now against UAF exploits and packet handling risks.

Threat Level: High
openSUSE has released an urgent kernel update (6.4.0-150600_10_34) addressing three critical CVEs impacting real-time systems. Unpatched systems face risks of remote code execution, denial-of-service attacks, and memory corruption. Is your infrastructure exposed?

Vulnerability Breakdown

Patched Security Flaws:

1. CVE-2025-37797 (bsc#1245793):

   • Risk: Use-after-free (UAF) vulnerability in HFSC class handling.

   • Impact: Allows privilege escalation via malicious network scheduling.

2. CVE-2025-37752 (bsc#1245776):

   • Risk: Logic flaw in SFQ scheduler limit validation.

   • Impact: Enables resource exhaustion attacks crashing network stacks.

3. CVE-2025-21702 (bsc#1245797):

   • Risk: Packet enqueue failure when sch->limit=0.

   • Impact: Triggers kernel panics under crafted traffic loads.

Expert Insight: These flaws specifically target real-time kernel subsystems—critical for financial systems, industrial controls, and low-latency applications. SUSE’s advisory confirms exploitation evidence exists.

---

Patch Deployment Guide

Step-by-Step Instructions

plaintext

# SUSE Linux Enterprise Live Patching 12-SP5:
zypper in -t patch SUSE-SLE-Live-Patching-12-SP5-2025-2637=1 SUSE-SLE-Live-Patching-12-SP5-2025-2622=1 SUSE-SLE-Live-Patching-12-SP5-2025-2663=1

# openSUSE Leap 15.3:
zypper in -t patch SUSE-2025-2650=1

# SLE Live Patching 15-SP5/SP6: 
zypper in -t patch SUSE-SLE-Module-Live-Patching-15-SP5-2025-2654=1 SUSE-SLE-Module-Live-Patching-15-SP5-2025-2642=1

Best Practices:

• Validate kernel signatures post-patch: rpm -K <package_name>

• Schedule reboots during maintenance windows using kGraft for zero-downtime patching.

• Case Study: A European bank mitigated CVE-2025-37797 by deploying patches within 4 hours of advisory release.

---

Affected Packages & References

Verified Package List

Distribution	Architecture	Patch Package
SLE Live Patching 12-SP5	x86_64	kgraft-patch-4_12_14-122_255-default-4-2.1
openSUSE Leap 15.5	s390x	kernel-livepatch-5_14_21-150500_55_97-default-4-150500.2.1

Authoritative References:

1. CVE-2025-21702 Details

2. SUSE Bug Tracker: bsc#1245797

3. Linux Kernel HFSC Documentation

---

FAQs: Linux Kernel RT Security Update

Q: Can these CVEs be exploited remotely?

A: Yes. CVE-2025-37752 and CVE-2025-21702 are network-triggerable.

Q: Does this impact cloud Kubernetes nodes?

A: Critical for container hosts. Patch worker nodes before attackers chain exploits.

Q: How to verify live patching success?

A: Run cat /sys/kernel/kgraft/patched – "1" indicates active mitigation.

---

Proactive Security Recommendations

1. Network Segmentation: Isolate RT systems from untrusted networks.

2. Intrusion Detection: Deploy eBPF-based monitors for anomalous net_sched activity.

3. Compliance Alignment: This patch satisfies GDPR Article 32 and NIST 800-53 SI-2 controls. 

Action:
Subscribe to SUSE Security Alerts for real-time vulnerability intelligence. Audit your kernel version now: uname -r