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CVE Record

CVE-2025-21687: vfio/platform: check the bounds of read/write syscalls

In the Linux kernel, the following vulnerability has been resolved: vfio/platform: check the bounds of read/write syscalls count and offset are passed from user space and not checked, only offset is capped to 40 bits, which can be used to read/write out of bounds of the device.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A local, low-privileged user could abuse missing bounds checks in Linux VFIO platform-device reads or writes to access data beyond the intended device region. Successful exploitation could compromise confidentiality, integrity, and availability. Systems not using or exposing VFIO platform devices are less likely to be reachable through this flaw.

Executive priority

Treat this as a high-priority local privilege-boundary issue on virtualization, device-assignment, and multi-user Linux systems. Accelerate patch validation where untrusted or lightly trusted users can access VFIO platform devices. Other systems should still be inventoried, but urgency should reflect actual interface exposure and vendor-confirmed package status.

Technical view

The vfio/platform read and write paths accepted user-controlled count and offset values without adequate bounds validation; only the offset was capped to 40 bits. This permitted out-of-bounds device access. The supplied CVSS 3.1 score is 7.8, reflecting local access, low complexity, low privileges, no user interaction, and potentially high impact.

Likely exposure

Exposure is most relevant on Linux systems where a low-privileged local user can reach an affected VFIO platform-device interface. Network-only attackers are not directly represented by the supplied vector. The bundled affected-version information is ambiguous, so distribution package and backport status must be confirmed with the applicable vendor.

Exploitation context

The supplied record is not in CISA KEV, and no provided source establishes active exploitation or a public exploit. Exploitation requires local, low-privileged access according to the CVSS vector. No indicators of compromise or reliable exploitation-detection method are included.

Researcher notes

The central defect is unchecked user-controlled length and offset handling in vfio/platform device I/O. Multiple stable-kernel commits are referenced, indicating backports across branches. However, the supplied affected-version array contains duplicated commit identifiers and unusual version entries, preventing a dependable fixed-version boundary from this bundle alone. Validate exact package provenance with the distributor.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable upstream VFIO platform bounds-check fix.
  • Confirm distribution backport status rather than relying only on the upstream kernel version number.
  • Restrict local account and VFIO device access while remediation is pending.
  • Follow vendor guidance for deployment, restart requirements, and any supported compensating controls.

Validation and detection

  • Inventory running kernel builds and systems exposing VFIO platform devices.
  • Map each distribution kernel package to its vendor advisory and upstream fix status.
  • After remediation, verify the updated kernel is actively running.
  • Confirm unauthorized users cannot access relevant VFIO device interfaces.
  • Document that the supplied sources provide no exploitation indicators or detection signatures.
Prepared
Confidence
medium
Sources
7

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-2025-21687 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
1ADP providers
15Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-21687Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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.

ADP provider summaries

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76a, 6e3f264560099869f68830cb14b3b3e71e5ac76aunaffected
LinuxLinux4.1, 0, 5.4.290, 5.4.291, 5.10.234, 5.10.235, 5.15.178, 5.15.179, 6.1.128, 6.1.129, 6.6.75, 6.12.12, 6.13.1, 6.14affected
Weakness

CWE details

No CWE listed

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