Service interruption via PRIO queue-length underflow
Published Jun 20, 2025 · Updated Aug 5, 2026
Race condition in Linux kernel PRIO scheduling from 5.0, including Siemens MFP firmware V3.1.5, allows local users to interrupt service. In prio_tune(), qdisc_tree_flush_backlog() releases the root lock before qdisc_put(), allowing an SFQ timer rehash to reduce backlog while packets remain queued. Exploitation requires local low-privilege access, a PRIO qdisc with an SFQ child, and winning the timer race; the bounded impact is service interruption.
Summary
What happened
Race condition in Linux kernel PRIO scheduling from 5.0, including Siemens MFP firmware V3.1.5, allows local users to interrupt service. In prio_tune(), qdisc_tree_flush_backlog() releases the root lock before qdisc_put(), allowing an SFQ timer rehash to reduce backlog while packets remain queued. Exploitation requires local low-privilege access, a PRIO qdisc with an SFQ child, and winning the timer race; the bounded impact is service interruption.
The record
- CVE
- CVE-2025-38083
- Published
- Jun 20, 2025
- Updated
- Aug 5, 2026
- Vendor
- Siemens
- Product
- SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
- Classifications
- CWE-362, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 20, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- 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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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