Kernel memory disclosure via swapped MIDI port counts
Published Mar 7, 2025 · Updated May 12, 2026
Information disclosure in Linux USB MIDI gadget support allows local users to expose uninitialized kernel stack memory to a connected host. The f_midi driver assigns the opposite port counts to bNumEmbMIDIJack and bLength, causing descriptors to include unwritten stack bytes. Exposure requires unequal input and output port counts and an active USB MIDI gadget connection; the receiving host obtains broken descriptors and leaked memory.
Summary
What happened
Information disclosure in Linux USB MIDI gadget support allows local users to expose uninitialized kernel stack memory to a connected host. The f_midi driver assigns the opposite port counts to bNumEmbMIDIJack and bLength, causing descriptors to include unwritten stack bytes. Exposure requires unequal input and output port counts and an active USB MIDI gadget connection; the receiving host obtains broken descriptors and leaked memory.
The record
- CVE
- CVE-2025-21835
- Published
- Mar 7, 2025
- Updated
- May 12, 2026
- Vendor
- Siemens
- Product
- SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
- Classifications
- T1005
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 7, 2025CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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- Affected versionversion=0 <*
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What is affected?
Attacks
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Weakness, pattern, technique
Public exploit references
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Your stack
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Your stack
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