The short answer is: No —
Azure Linux is not necessarily the only Microsoft product that could include the vulnerable ath9k_htc code, but it is the only Microsoft product Microsoft has publicly attested so far as “including this open‑source library and therefore potentially affected.” That attestation is authoritative for Azure Linux customers and should be acted on immediately, but it is not a proof of exclusivity for all Microsoft artifacts. rview
CVE-2025-38157 is a Linux kernel vulnerability in the ath9k_htc wireless USB driver. A malicious USB device can send a WMI_SWBA_EVENTID event from an ath9k_htc‑managed device before beaconing is enabled, which leads to a division-by-zero error in the driver and can cause a crash or an out‑of‑bounds read. Upstream kernel maintainers fixed the root cause by aborting the handler when beacons are not yet enabled. This technical description is recorded in multiple vulnerability databases and the upstream stable kernel commit history.
Microsoft’s published CVE note for this class of Linux kernel issues follows a standard pattern: for some CVEs Microsoft lists the product(s) it has inventory‑checked and attested as carriers of the implicated open‑source component. In the CVE page language the company uses the wording that “Azure Linux includes this open‑source library and is therefore potentially affected,” and it also states that it will update the CVE/VEX/CSAF mapping if additional Microsoft products are identified as carriers. That phrasing is an explicit inventory attestation for Azurmrosoft product could ever contain the same kernel code.
Why this question matters to defenders and administrators
Enterprise and cloud operators frequently treat vendor attestations as gating signals for remediation. Microsoft’s attestation that
Azure Linux includes the vulnerable library is immediately actionable for customers running that distribution: patch those images, rebuild node pools, and plan maintenance windows. However, because the vulnerable code is upstream kernel code, any Microsoft artifact that ships a kernel (or kernel module) built from an affected tree — including WSL2 kernels, linux-azure kernels used by certain VM images, Marketplace images, container base images that embed kernel module tarballs in build pipelines, or custom appliances built by Microsoft partners —
could include the same driver and therefore be in scope. You cannot assume “not affected” simply bux appears on the MSRC entry today.
Key operational implications:
- Treat Microsoft’s attestation as a high‑confidence signal for Azure Linux images; prioritize t- Treat other Microsoft Linux artifacts (WSL kernels, linux-azure builds, Marketplace images, managed node images, AKS node images, developer tool kernels) as unknown until verified — perform artifact‑level checks.
-omy — what exactly is ath9k_htc and why it appears in many places
ath9k_htc is the in‑tree Linux kernel driver that supports Atheros AR9xxx family USB Wi‑Fi chipsets (for example AR9271 and related bridging hardware). It is built as a kernel module named ath9k_htc when the kernel config enables the Atheros HTC support. That driver is present in long‑term and stable kernel series used by major Linux distributions, and distribution kernel packages commonly include ath9k_htc as a module, which means the same upstream source can be present in many vendor kernel builds. Documentation and kernel configuration references confirm the driver’s location in drivers/net/wireless/ath/ and list the module as ath9k_htc.
Because it is an optional kernel module (dependent on kernel config options like CONFIG_USB and CONFIG_MAC80211), the practical exposure of any given host depends on:
- Whether the running kernel build included the module (does the host have /lib/modules/$(uname -r)/kernel/drivers/net/wireless/ath/ath9k_htc.ko?).
- Whether the module is loaded at runtime (lsmod/modprobe behavior).
- Whether the host has the relevant Atheros USB hardware or runs virtual/test harnesses that may load the module.
In large cloud images and server fleets, wireless drivers are often present in the kernel build but not loaded, which reduces remote exploitation risk. Nonetheless, the presence of the binary module file inside an image or kernel package is enough for Microsoft (or any vendor) to map the upstream component to a product and declare the product “potentially affected.”
What Microsoft’s statement actually says — and what it does not
Microsoft’s MSRC-style wording — “Azure Linux includes this open‑source library and is therefore potentially affected” — is a product‑level inventory attestation. It means Microsoft scanned the Azure Linux build artifacts and found the upstream component referenced by the CVE in those artifacts. That is valuable because it tells Azure Linux customers exactly which product is in scope without forcing every customer to perform a full binary scan of hosted images. However, the sentence intentionally stops short of making any claim about other Microsoft products. Microsoft has also publicly committed to expanding machiatically and to update CVE mappings if it identifies additional affected products.
Put another way:
- Affirmative: Microsoft has confirmed Azure Linux as a carrier for the affected upt product should be remediated per Microsoft/distro guidance.
- Negative (implicit): Microsoft’s attestation for Azure Linux does not logically prove that no other Microsoft product contains the same vulnerable slic attestation is not proof of absence.
This is common industry practice: large vendors publish attestations as their per‑product inventory work completes. Customers and operators must combine vendor attestations with their own artifact discovery and SBO complete coverage.
Independent verification — what public trackers and distributions show
Multiple independent sources document CVE-2025-38157 and the upstream fix. At a minimum you should cross‑check:
- The NVD / CVE record, which lists the technical summary and tracks the CVE lifecycle.
- OSV / upstream CVE entries which link to the kernel commits and stable backports.
- Major distribution advisories and kernel changelogs (Ubuntu, SUSE, Red Hat families, and linux-azure changes) that map the CVE to particular kernel package updates. For example, Ubuntu’s CVE entry and changelogs include the ath9k_htc description and status, and linux-azure changelogs list CVE-2025-38157 as fixed in an updated upstream stable patchset.
Those independent traces confirm that:
- The vulnerability exists in upstream kernel trees and was fixed with a small, targeted change to abort handling when beacons are disabled, and
- Multiple distributions have incorporated the stable patch into their kernel releases or backport packages.
Because the same upstream kernel code is consumed by many distributions and image builders, this corroborates the point that the presence of the code in Azure Linux is not inherently unique.
Practical verification steps for operators (concrete, repeatable checks)
If you run Microsoft‑supplied artifacts or images in your environment, prioritize Azure Linux images first, then perform an artifact sweep across other Microsoft artifacts you operate. Below are prioritized, repeatable checks (the commands are standard Linux diagnostics):
- Identify the running kernel and vendor build:
- uname -r
- cat /proc/version
- Check whether the ath9k_htc module binary exists for the running kernel:
- ls -R /lib/modules/$(uname -r) | grep -i ath9k_htc
- Check whether the module is loaded:
- sudo lsmod | grep -i ath9k_htc
- sudo modinfo ath9k_htc 2>/dev/null || echo "ath9k_htc not present"
- Inspect kernel logs for relevant warnings or OOPS messages:
- sudo dmesg | grep -i 'ath9k_htc|WMI_SWBA_EVENTIournalctl -k | grep -i 'ath9k_htc'
- For WSL2:
- From Windows PowerShell (elevated): wsl --update ; wsl --shutdown
- Inside WSL: uname -r, then run the module checks above to confirm whether the Microsoft-provided WSL kernel includes the module. Note: WSL kernels are Microsoft-distributed; if a WSL kernel includes thicrosoft distributes updates to WSL separately.
- For Azure Marketplace images, AKS node images, or node pools:
- Boot a representative instance, run the same kernel and module checks, or consult image metadata and publisher-provided SBOMs if available. For AKS, enumerate node OS/kernel with kubectl get nodes -o wide SSH into a node to validate.
- If you find the module present and cannot patch immediately:
- Short term mitigation: blacklist the module (echo "blacklist ath9k_htc" > /etc/modprobe.d/ath9k_htc.conf and rebuild initramfs if needed), or ensure wireless functionality is disabled in images that do not need it. This reduces the local attack surface.
These checks let you move from vendor attestation to artifact‑level verification — the only reliable way to determine whether a specific image or product is actually carrying the vulnerable code.
Where Microsoft products beyond Azure Linux might hide vulnerab supply‑chain and image‑management perspective, the following Microsoft artifacts are plausible carriers and should be validated when you operate them:
- WSL2 kernels distributed by Microsoft or custom WSL kernels used in development images. WSL kernels are updated independently of Azure Linux and should be included in any sweep.
- linux-azure kernel packages used for some Azure VM SKUs and images (separate from the Azure Linux distribution). The linux-azure changelog itself lists CVE-2025-38157 in upstream updates, indicating that kernel builds used by Azure images are tracked.
- Marketplace images and partner images that use Microsoft-provided base images, or images built from Azure Lneage matters; a vulnerable kernel in a base image can propagate into many derived images.
- Developer tooling and appliances (for example, Docker Desktop, CI worker images, or testing harnesses) if they ship or embed kernel modules or custom kernels. Kernel modules can also be bundled in container layers used only during image creation; these must be scanned as well.
Because the kernel is a compiled artifact and vendors will sometimes backport fixes or selectively enable/disable modules, the only certain way to confirm for any Microsoft product is artifact inspection — i.e., examine the shipped kernel binary, module tree, or vendor-supplied ths and limitations of Microsoft’s approach
Strengths:
- Microsoft’s product-level attestation for Azure Linux gives clear, actionable guidance to customers using that distro — they now know to prioritize those images for remediation. The company’s commitment to publish CSAF/VEX attestations improves transparency and enables automation for response.
- The fix is upstream, small, and stable, which makes it straightforward for distributions and cloud vendors to backport and ship kernel updates; multiple distros have already mapped the fix into kernel packages. This reduces the time-to-remediation once vendors release updates.
Limitations and residual risks:
- Product-level attestations are only complete if the vendor has inspected every product image and artifact; Microsoft explicitly states they wappings when new products are identified, which implies the mapping is iterative rather than exhaustive. Customers should therefore not use a lack of attestation as a guarante “long tail” problem remains: embedded, partner-supplied, or long-lived VM images may not be updated promptly. These images can remain carriers of the vulnerable kernel code for months. That is a systemic problem across vendors and not unique to Microsoft.
- Detection is noisy: kernel OOPSes and WARN_ONs may bebugs, so telemetry must be correlated with artifact inventory to focus remediation effectively.
Recommended action plan for WindowsForum readers and administrator)
- Patch any Azure Linux images and node pools you control — Microsoft explicitly attested Azure Linux as a carrier and customers should treat those images as in‑scope. Prioritize rebuilds and rolling updates.
- For hosts where wireless is not required, temporatc or disable wireless modules to reduce attack surface until patched images are available.
- Short term (days)
- Run the artifact verification checklist across all Microsoft-supplied artifacts you operate: WSL2 kernels, linux-azure kernels, Marketplace images, AKS node images, CI images. Use the module presence checks and kernel log inspection steps above.
- Apply patched vendor kernel packages where available (Ubuntu, SUSE, RHEL-family, etc.). Confirm kernel package versions match vendor advisories that list CVE-2025-38157.
- Medium term (weeks)
- Integrate kernel CVE tracking and image SBOM verification into your CI/CD and imo future kernel fixes are visible and routable into automated rebuilds.
- For managed services (AKS, Marketplace images), demand publisher attestation (SBOM or a VEX response) before trusting images in production.
- Forensics and detection
- Add SIEM rules to capture kernel oops/WARN_ON traces that reference ath9k_htc or WMI_SWBA_EVENTID. If you see repeated kernel OOPS patterns on hosts that also have the module present, escalate and patch immediately.
Conclusion
Microsoft’s statement that “Azure Linux includes this open‑source library and is therefore potentially affected” is an important, actionable attestation: if you run Azure Linux images, treat them as in‑scope and remediate now. However, that wording does not mean Azure Linux is the only Microsoft product that could include the ath9k_htc driver. Because ath9k_htc is upstream kernel code that appears in many distributions and kernel builds, any Microsoft artifact that ships a kernel built from an affected tree (WSL kernels, linux-azure kernels, Marketplace images, managed node images, or derivative images) could also carry the vulnerable module — and those artifacts must be verified at the binary/artifact level.
Practers are clear: prioritize patching of attested artifacts (Azure Linux), run the artifact checks listed above across other Microsoft-supplied kernels and images you operate, and apply vendor kernel patches or temporary mitigations where necessary. Microsoft’s attestation is a starting point — useful and authoritative for the product it names — but complete assurance depends on artifact-level verification and the vendor’s ongoing VEX/CSAF updates.
Source: MSRC
Security Update Guide - Microsoft Security Response Center