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CVE Record

CVE-2025-40085: ALSA: usb-audio: Fix NULL pointer deference in try_to_register_card

In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: Fix NULL pointer deference in try_to_register_card In try_to_register_card(), the return value of usb_ifnum_to_if() is passed directly to usb_interface_claimed() without a NULL check, which will lead to a NULL pointer dereference when creating an invalid USB audio device. Fix this by adding a check to ensure the interface pointer is valid before passing it to usb_interface_claimed().

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can crash affected systems when a malformed or invalid USB audio device is handled. The public record does not provide CVSS, CWE, or confirmed exploitation. Business urgency depends on whether users, guests, or connected infrastructure can attach USB audio devices to Linux hosts.

Executive priority

Treat this as a kernel stability and local exposure issue, not a confirmed internet-scale emergency. Patch through normal kernel maintenance, accelerating for systems where untrusted USB devices can be attached.

Technical view

The ALSA usb-audio path in try_to_register_card() passes usb_ifnum_to_if() directly to usb_interface_claimed() without checking for NULL. An invalid USB audio device can trigger a NULL pointer dereference. The fix adds an interface pointer validity check before use.

Likely exposure

Exposure is most plausible on Linux systems running affected kernel builds with USB audio support and accessible USB device attachment. Risk is higher for endpoints, kiosks, labs, and virtualized environments that can present USB audio devices.

Exploitation context

The bundle says KEV is false and provides no cited evidence of active exploitation. The described trigger involves creating or presenting an invalid USB audio device; the source does not support claims of remote exploitation or privilege escalation.

Researcher notes

Evidence supports a NULL pointer dereference in ALSA usb-audio only. The record lacks CVSS, CWE, exploit reports, and detailed downstream package mapping, so validation should focus on kernel lineage and presence of the stable fix.

Mitigation direction

  • Update to a kernel build containing the referenced stable fix.
  • Use distribution advisories to map the fix to supported packages.
  • Restrict untrusted physical or virtual USB audio device attachment until patched.
  • Prioritize endpoints, kiosks, and systems with accessible USB ports.

Validation and detection

  • Inventory running Linux kernel versions across assets.
  • Check package changelogs or git history for the referenced fix commits.
  • Identify hosts where USB audio modules or devices are enabled.
  • Confirm no source reports active exploitation before changing incident severity.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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

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CVE-2025-40085 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
3Timeline events
0ADP providers
7Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux28787ff9fbeaf57684eb64cc33e2ec8ceedf21b5, 39efc9c8a973ddff5918191525d1679d0fb368ea, 39efc9c8a973ddff5918191525d1679d0fb368ea, 39efc9c8a973ddff5918191525d1679d0fb368ea, 39efc9c8a973ddff5918191525d1679d0fb368ea, 39efc9c8a973ddff5918191525d1679d0fb368ea, 9d4f4dc3cd38e412c29a7626489fe48b79ebbf6c, 52076a41c128146c9df4a157e972cb17019313b1, 5.15.75, 5.19.17, 6.0.3unaffected
LinuxLinux6.1, 0, 5.15.196, 6.1.158, 6.6.114, 6.12.55, 6.17.5, 6.18affected
Weakness

CWE details

No CWE listed

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