Kernel crash via empty HTB priority tree
Published Jul 28, 2025 · Updated Jul 14, 2026
Denial of service in the Linux kernel HTB scheduler allows local users to crash the kernel through a crafted qdisc hierarchy. When netem drops the sole queued packet, HTB removes its only priority-tree class, yet htb_dequeue_tree calls htb_lookup_leaf again and reaches BUG_ON on the empty tree. Exploitation requires local low-privileged access to configure the affected HTB, netem, and blackhole queueing disciplines; the resulting assertion interrupts the system.
Summary
What happened
Denial of service in the Linux kernel HTB scheduler allows local users to crash the kernel through a crafted qdisc hierarchy. When netem drops the sole queued packet, HTB removes its only priority-tree class, yet htb_dequeue_tree calls htb_lookup_leaf again and reaches BUG_ON on the empty tree. Exploitation requires local low-privileged access to configure the affected HTB, netem, and blackhole queueing disciplines; the resulting assertion interrupts the system.
The record
- CVE
- CVE-2025-38468
- Published
- Jul 28, 2025
- Updated
- Jul 14, 2026
- Vendor
- Siemens
- Product
- SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
- Classifications
- CWE-476, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 28, 2025CVE publishedPublication date reported by the CVE source.
- Jul 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=V3.1.5 <*
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- HTB empty-priority-tree reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo