# CVE-2026-90398: wifi: ath11k: fix stride mismatch in mac_phy_caps_parse()

> A stride mismatch in the ath11k WiFi driver allows out-of-bounds writes when processing short firmware TLVs, potentially leading to memory corruption or crashes.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **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:** AZL-101936, BELL-CVE-2026-90398, DEBIAN-CVE-2026-90398, GHSA-vrcf-5rpv-m35r, UBUNTU-CVE-2026-90398

## What is CVE-2026-90398?

CVE-2026-90398 is a high-severity memory corruption 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:

wifi: ath11k: fix stride mismatch in mac_phy_caps_parse()

Currently, in ath11k_wmi_tlv_mac_phy_caps_parse(), kcalloc() sizes the
mac_phy_caps buffer as tot_phy_id * len, where len is clamped to
min(firmware_len, sizeof(struct wmi_mac_phy_capabilities)). The subsequent
memcpy() destination advances by sizeof(full struct) per slot via C
pointer arithmetic, not by the clamped len. When firmware sends short
TLVs, the second and later slots are written past the end of the
allocation.

The reader in ath11k_pull_mac_phy_cap_svc_ready_ext() also indexes the
buffer with full-struct pointer arithmetic, so the allocation must match
that stride.

Fix by using kzalloc_objs(), which derives the element size from the
pointer type, making allocation size and pointer stride provably
consistent regardless of what len the firmware provides.

Compile tested only.

## Which versions are affected by CVE-2026-90398?


## How do I fix CVE-2026-90398?

Apply the vendor's patch.

## Is CVE-2026-90398 being exploited?

There is no known exploitation of CVE-2026-90398 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90398 and fix it if it is affected.

What it is: CVE-2026-90398 is a high-severity memory corruption 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-2026-90398 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-2026-90398/ (Markdown: https://insights.sbomify.com/CVE-2026-90398/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90398
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90398
- OSV: https://osv.dev/vulnerability/CVE-2026-90398

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90398/
Summaries are generated and may contain mistakes; the official description above is the record.