# CVE-2026-90240: iommu/vt-d: Flush context cache with correct SID when tearing down aliases

> A use-after-free vulnerability in the Linux kernel IOMMU driver allows attackers to execute arbitrary code or escalate privileges via stale cache entries.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-90240, DEBIAN-CVE-2026-90240, GHSA-rghx-9889-ffmw, UBUNTU-CVE-2026-90240

## What is CVE-2026-90240?

CVE-2026-90240 is a high-severity use after free vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

iommu/vt-d: Flush context cache with correct SID when tearing down aliases

domain_context_clear_one() and device_pasid_table_teardown() are both
invoked once per DMA alias of a device. Each function locates the context
entry using the bus/devfn pair provided by the pci_for_each_dma_alias()
callback, then calls intel_context_flush_no_pasid(), which constructs a
device-selective context-cache invalidation from info->bus and
info->devfn (that is, always the requester ID of the device itself).

As a result, for every alias other than the device’s own RID, the context
entry that was just cleared in memory is never invalidated in the context
cache. Hardware may continue using that stale cached entry. In the
scalable-mode teardown path, intel_pasid_free_table() can then free the
PASID directory still referenced by that stale entry, allowing the IOMMU
to walk freed memory.

Fix this by passing the source ID of the entry being torn down to
intel_context_flush_no_pasid(), instead of deriving it from @info.

## Which versions are affected by CVE-2026-90240?


## How do I fix CVE-2026-90240?

Apply the vendor's patch.

## Is CVE-2026-90240 being exploited?

There is no known exploitation of CVE-2026-90240 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90240 and fix it if it is affected.

What it is: CVE-2026-90240 is a high-severity use after free vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90240 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90240/ (Markdown: https://insights.sbomify.com/CVE-2026-90240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90240
- OSV: https://osv.dev/vulnerability/CVE-2026-90240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90240/
Summaries are generated and may contain mistakes; the official description above is the record.