Security readout for executives and security teams
Plain-English summary
CVE-2025-21859 is a Linux kernel availability bug in the USB gadget MIDI function. When USB MIDI is used, the kernel can try to take the same lock twice and deadlock. The documented impact is denial of service, not data theft or code execution.
Executive priority
Schedule remediation through normal kernel or firmware maintenance, with higher priority for embedded, shared, or locally accessible devices using USB gadget MIDI. This is not supported as actively exploited in the provided sources, but it can affect availability.
Technical view
The flaw is CWE-667 in the Linux kernel USB gadget f_midi path. A completion handler can re-enter f_midi_transmit and attempt recursive lock acquisition, causing a deadlock. The kernel fix schedules the inner transmit through queue_work on a high-priority workqueue.
Likely exposure
Exposure appears narrow: Linux systems or embedded devices that enable and use the USB gadget MIDI function. General-purpose servers without USB gadget MIDI are less likely to be affected. Siemens and Debian references indicate downstream product and distribution relevance, but the bundle does not define all affected products.
Exploitation context
The CVSS vector is local, low complexity, low privileges, no user interaction, availability-only impact. The bundle does not report CISA KEV listing or active exploitation. Treat this as a local denial-of-service risk where USB gadget MIDI is reachable.
Researcher notes
The useful validation focus is configuration and reachability, not remote exposure. The bundle names the code path and fix strategy but does not provide complete downstream product coverage. Avoid assuming exploitability beyond local availability impact from the CVSS vector.
Mitigation direction
- Apply Linux kernel updates containing the referenced stable fixes.
- Check Debian LTS and vendor advisories for packaged kernel updates.
- For appliances, request vendor firmware guidance before changing kernels manually.
- Disable unused USB gadget MIDI functionality where operationally safe.
- Prioritize systems where local users or tenants can access gadget MIDI paths.
Validation and detection
- Inventory Linux kernel versions across affected device classes.
- Confirm whether USB gadget MIDI support is built, loaded, or configured.
- Map running kernels against vendor fixed package or firmware advisories.
- Review Debian LTS and device vendor notices for applicable versions.
- Test remediation in representative devices before broad deployment.
Public sources used
- CVE Program
- CVE List V5
- Linux stable fix 727dee0857946b85232526de4f5a957fe163e89a
- Linux stable fix 1f10923404705a94891e612dff3b75e828a78368
- Linux stable fix b09957657d7767d164b3432af2129bd72947553c
- Linux stable fix 24a942610ee9bafb2692a456ae850c5b2e409b05
- Linux stable fix deeee3adb2c01eedab32c3b4519337689ad02e8a
- Linux stable fix e9fec6f42c45db2f62dc373fb1a10d2488c04e79
- Linux stable fix 8aa6b4be1f4efccbfc533e6ec8841d26e4fa8dba
- Linux stable fix 4ab37fcb42832cdd3e9d5e50653285ca84d6686f
- Debian LTS advisory May 2025 msg00045
- Debian LTS advisory May 2025 msg00030
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-667: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-21859 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/727dee0857946b85232526de4f5a957fe163e89aCVE reference, Linux
- https://git.kernel.org/stable/c/1f10923404705a94891e612dff3b75e828a78368CVE reference, Linux
- https://git.kernel.org/stable/c/b09957657d7767d164b3432af2129bd72947553cCVE reference, Linux
- https://git.kernel.org/stable/c/24a942610ee9bafb2692a456ae850c5b2e409b05CVE reference, Linux
- https://git.kernel.org/stable/c/deeee3adb2c01eedab32c3b4519337689ad02e8aCVE reference, Linux
- https://git.kernel.org/stable/c/e9fec6f42c45db2f62dc373fb1a10d2488c04e79CVE reference, Linux
- https://git.kernel.org/stable/c/8aa6b4be1f4efccbfc533e6ec8841d26e4fa8dbaCVE reference, Linux
- https://git.kernel.org/stable/c/4ab37fcb42832cdd3e9d5e50653285ca84d6686fCVE reference, Linux
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.htmlCVE reference, CVE
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.htmlCVE reference, CVE
- https://cert-portal.siemens.com/productcert/html/ssa-265688.htmlCVE reference, siemens-SADP
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Locking
Improper Locking represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.