iommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE (CVE-2026-74573) | HOL Guard CVE

Critical · CVSS 9.3CVE-2026-74573

iommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE

Answer in brief

CVE-2026-74573 records a Critical severity (CVSS 9.3) vulnerability in iommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 15, 2026Updated Aug 17, 2026Source checked Sep 30, 2026First seen by HOL Aug 15, 2026Material review Aug 17, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.3
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 9.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=d68beb276ba26cec47350a6d468e967673ee0c56 <3808bab5d95ae79e333e11f6a73d178e084c645d \|\| >=d68beb276ba26cec47350a6d468e967673ee0c56 <0acbc621341aca4eb94d9c2f43e1ab273ff088f0 \|\| >=d68beb276ba26cec47350a6d468e967673ee0c56 <c3b8ee84a965058b41275069d4696f37a8b14bf6	3808bab5d95ae79e333e11f6a73d178e084c645d, 0acbc621341aca4eb94d9c2f43e1ab273ff088f0, c3b8ee84a965058b41275069d4696f37a8b14bf6
Linux/Linuxgeneric	6.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 3808bab5d95ae79e333e11f6a73d178e084c645d if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 15, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 15, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: iommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE arm_vsmmu_vsid_to_sid() maps a guest's vSID to a single physical Stream ID taken from master->streams[0], assuming a device has exactly one stream. A device with several streams gets only its first one mapped, so a guest vSID invalidation cannot reach the others' ATC and IOTLB entries; a device with none makes master->streams a ZERO_SIZE_PTR, read out of bounds. Add an arm_vsmmu_vdevice_init() op to reject the vDEVICE with -EOPNOTSUPP when master->num_streams is not one, rather than mapping it silently.

Quoted source text, attributed separately from HOL analysis.