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CVE Record

CVE-2025-40031: tee: fix register_shm_helper()

In the Linux kernel, the following vulnerability has been resolved: tee: fix register_shm_helper() In register_shm_helper(), fix incorrect error handling for a call to iov_iter_extract_pages(). A case is missing for when iov_iter_extract_pages() only got some pages and return a number larger than 0, but not the requested amount. This fixes a possible NULL pointer dereference following a bad input from ioctl(TEE_IOC_SHM_REGISTER) where parts of the buffer isn't mapped.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2025-40031 is a Linux kernel bug in TEE shared-memory registration. Bad local input to a TEE ioctl can hit incorrect error handling and may trigger a NULL pointer dereference. The public record does not provide CVSS, CWE, or confirmed impact beyond the possible crash condition.

Executive priority

Treat this as a normal-priority kernel update unless TEE interfaces are exposed to untrusted local users. There is no sourced evidence of active exploitation, but kernel NULL dereference bugs can affect availability on shared systems.

Technical view

The issue is in register_shm_helper() handling of iov_iter_extract_pages(). Partial page extraction, returning more than zero but less than requested, was not handled correctly. With partially unmapped user buffers passed to ioctl(TEE_IOC_SHM_REGISTER), later code may dereference NULL.

Likely exposure

Exposure is most likely on Linux systems running affected kernel versions with the TEE subsystem and reachable TEE device interfaces. Confirm exposure against the specific vendor kernel, because distributions may backport fixes without changing major version numbers.

Exploitation context

The source bundle does not show KEV listing or public active exploitation. The described trigger requires bad input to a local ioctl path, so this should be treated as a local kernel reliability risk unless vendor analysis says otherwise.

Researcher notes

Key uncertainty remains around exact affected version ranges and vendor backports. The public description supports a partial iov_iter_extract_pages() error-handling flaw and possible NULL dereference, but not privilege escalation, remote reachability, or exploit availability.

Mitigation direction

  • Apply vendor kernel updates containing the referenced Linux stable fixes.
  • Check Linux distribution advisories for backported fixed kernels.
  • Limit unnecessary user or container access to TEE device nodes.
  • Prioritize updates on multi-user systems exposing TEE interfaces.

Validation and detection

  • Inventory kernels and identify systems using affected Linux versions or vendor builds.
  • Check whether referenced stable commits are present in the running kernel source package.
  • Review device permissions for TEE interfaces on exposed hosts.
  • Monitor vendor advisories for corrected package versions and impact notes.
Prepared
Confidence
medium
Sources
5

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

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CVE-2025-40031 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
4Source 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
LinuxLinux7bdee41575919773818e525ea19e54eb817770af, 7bdee41575919773818e525ea19e54eb817770af, 7bdee41575919773818e525ea19e54eb817770afunaffected
LinuxLinux6.8, 0, 6.12.53, 6.17.3, 6.18affected
Weakness

CWE details

No CWE listed

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