CVE-2024-44997: Azure Linux Attestation and MediaTek WED Kernel Patch

A recently assigned Linux-kernel vulnerability — CVE-2024-44997 — patches a use‑after‑free bug in the MediaTek WED (Wireless Ethernet Device) driver that can cause a kernel panic on MT798X‑class hardware, and Microsoft’s public advisory names Azure Linux as the Microsoft product that includes the implicated upstream code and is therefore potentially affected. That Microsoft attestation is important and actionable for Azure Linux users, but it is not a technical guarantee that no other Microsoft product could ship the same vulnerable kernel code; absence of a public attestation is absence of attestation, not proof of absence.

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Background / Overview​

What CVE‑2024‑44997 is, in plain terms​

CVE‑2024‑44997 is a kernel‑level use‑after‑free in the MediaTek Ethernet offload/driver code (mtk_wed). Under a narrow, but realistic condition — when multiple AP (access point) interfaces share a radio band while the WED feature is enabled — bringing an AP interface down could leave a pointer (cb_priv) dangling and later dereferenced, producing an invalid memory access and causing a kernel panic on MT798X platforms. The upstream remedy is straightforward: free the private callback data and immediately set the pointer to NULL, and add a defensive NULL‑check in the callback path. The fix was merged into the stable kernel trees via small, targeted commits.

How severe is it?​

Vendor scoring varies but the widely referenced NVD listing records a high base CVSS score (7.8) because the defect can lead to kernel panic and potential denial of service in affected configurations. Some distribution feeds use different scoring or contextual severity assessments (for example, some downstream providers label it as medium when judged against their particular threat model). What matters for operators is not just the numerical score but the exploitability conditions: this is a local, kernel‑level bug that requires WED to be enabled and the presence of MediaTek MT798X hardware or a kernel configuration that includes the affected driver.

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What Microsoft said — and what that wording actually means​

The Microsoft attestation: product‑scoped, not global​

Microsoft’s public advisory language follows a pattern you’ll increasingly see in modern vendor disclosures: it declares that Azure Linux includes the implicated open‑source component and is therefore potentially affected, and it also states Microsoft’s commitment to publish machine‑readable attestations (CSAF/VEX) and to update the CVE mapping if other Microsoft products are later identified as carriers of the same upstream code. This is deliberate: the first statement is an inventory attestation for a named product family; the second is a process promise describing how Microsoft will publish and expand those attestations.
Put simply:

• The Azure Linux attestation is authoritative for Azure Linux images Microsoft manages; if you run Azure Linux you should treat that signal as definitive and act on it.
• The attestation does not claim that every Microsoft SKU has been fully scanned and verified as unaffected. Microsoft’s phrasing explicitly leaves open the possibility that additional Microsoft products may later be identified and added to the VEX/CSAF mapping.

Why vendors use product‑scoped attestations​

There are practical reasons for per‑product attestations:

• Microsoft and other major vendors distribute many distinct artifacts (different kernel builds, customized kernels, marketplace images, container base images and so on). Whether a given artifact contains vulnerable upstream code depends on:
  • the exact kernel version/commit range used,
  • which upstream commits were applied when the kernel was built,
  • the kernel CONFIG_* build options (modules vs built‑in),
  • and what driver modules are enabled for a target product image.
• Performing an exhaustive, artifact‑level inventory across thousands of SKUs and partner‑published images is operationally heavy; a phased rollout that begins with a single product (Azure Linux) and expands outward is a pragmatic path toward machine‑readable transparency. Microsoft documented that phased approach when it launched machine‑readable VEX/CSAF support in October 2025.

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Are other Microsoft products potentially affected?​

Short answer​

No, Azure Linux is not necessarily the only Microsoft product that could include the vulnerable code — it is simply the only Microsoft product Microsoft has publicly attested (so far) to include the upstream component implicated by CVE‑2024‑44997. That attestation is authoritative for Azure Linux, but other Microsoft artifacts may still carry the same upstream driver depending on their kernel builds and configurations, and the absence of a VEX/CSAF entry for another product is not a guarantee that the product is clean.

Which Microsoft artifacts are worth checking​

Operators and security teams should treat the following Microsoft artifacts as higher‑priority candidates to verify, because they are Microsoft‑maintained or Microsoft‑distributed kernel images where inclusion of upstream drivers is plausible:

• Azure Linux (attested by Microsoft) — patch or apply the vendor‑provided update.
• linux‑azure / kernel‑azure packages used by certain public cloud images or partner images — these packages are Microsoft‑curated kernel builds and can carry upstream drivers; vendor advisories have identified "kernel‑source‑azure" in their affected lists for related CVEs in the past.
• The Microsoft‑published WSL2 kernel binary and its source repository (if the WSL2 kernel configurations include the mtk_wed driver).
• Any Azure Marketplace VM images or custom Microsoft images that embed Microsoft‑built kernel packages.
• Specialized appliances and thin images where Microsoft supplies a kernel build (for example, some Azure edge images or partner appliances packaged via the Azure Marketplace).

For each of those artifacts, the only reliable way to know is artifact‑level verification: either consult Microsoft’s VEX/CSAF attestations for that specific product or inspect the image/kernel you run. Microsoft has committed to update VEX/CSAF mappings as it discovers additional affected products, but until that update appears, operators must perform their own checks.

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Evidence and cross‑checks (what I verified)​

To ensure the analysis is grounded in multiple independent sources I reviewed and cross‑checked the following:

• Upstream vulnerability description and merged fixes in the kernel trees (commit references and the kernel stable patches). These confirm the code path and the exact repair (NULL assignment after free and defensive NULL check). Multiple kernel commits were included in the public patch metadata.
• Official vulnerability records and vendor trackers: the NVD entry and distribution advisories (Ubuntu, Debian, SUSE and Amazon Linux advisories) which reproduce the upstream description and list affected kernel ranges for various distributions. These sources independently confirm the technical details and the distribution‑level remediation status.
• Microsoft’s own transparency announcement about publishing CSAF/VEX attestations, which documents the October 2025 rollout and explains that VEX is being used to map third‑party CVEs against product inventories, beginning with Azure Linux. That context explains the meaning of Microsoft’s Azure Linux attestation and its workplan to expand attestations.
• Independent vulnerability databases and security vendors (OpenCVE, Wiz, cvefeed) that record both the CVE metadata and the kernel patch references; these provide cross‑validation for the kernel commit IDs and the remediation approach.

Where Microsoft explicitly declared a product mapping (Azure Linux), I treated that as an authoritative vendor statement; where Microsoft has not yet declared a product mapping, I flagged the result as unverified and recommended artifact checks. The file uploads in your workspace include prior forum guidance that reaches the same conclusion: Microsoft’s Azure Linux attestation is product‑scoped and not proof that all Microsoft products are unaffected.

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What operators and security teams should do now​

If you manage Azure Linux images

• Treat Microsoft’s attestation as affirmative. Apply the vendor patch or update Azure Linux images according to Microsoft’s guidance and your patching windows. If you rely on Azure Marketplace images that are maintained by Microsoft, those images will usually roll the fix in a timely manner.

If you manage other Microsoft‑branded or Microsoft‑distributed artifacts (WSL2, linux‑azure kernels, Marketplace images)

• Don’t assume safety. Run artifact‑level checks and/or consult Microsoft’s machine‑readable VEX/CSAF outputs for the specific product SKU. Microsoft has committed to expand VEX/CSAF attestations beyond Azure Linux, but until your product is listed you must verify yourself.

If you need a practical, repeatable approach, here’s a short checklist you can run across a fleet.

1. Identify candidate kernels and images:
   • Inventory all hosts where Linux runs under your control: cloud VMs, on‑prem appliances, WSL2 instances managed by users, edge devices and so on.
2. Check kernel version and configuration:
   • For a running host: check uname -r to capture the kernel version and then check the compiled config (for example, /proc/config.gz or /boot/config-$(uname -r)).
   • Look for the presence of MediaTek driver modules or built‑in drivers related to WED, e.g., search for drivers/net/ethernet/mediatek or for mtk_wed in the kernel config/module list.
3. Inspect the image or kernel package itself:
   • If you have access to the kernel image or package (RPM, DEB, kernel‑source), search the source tree for the mtk_wed files or for the specific commit ranges that include the vulnerable code.
4. If in doubt, repro the condition in a safe test environment:
   • If you have hardware that matches MT798X or images that might include the driver, reproduce the condition with WED enabled (in a test lab) to see whether the kernel panic occurs. Don’t do this on production systems.
5. Apply vendor patches where available:
   • For Azure Linux, install the Microsoft‑published update. For vendor images that are third‑party (Ubuntu, Debian, SUSE), follow the respective distro advisory for the correct kernel/stable update.

Below is a minimal example of commands to detect likely exposure on a Linux host:

• uname -r
• zgrep -i mtk_wed /proc/config.gz || grep -R "mtk_wed" /lib/modules/$(uname -r) || find /usr/src -name 'mtk_wed'
• lsmod | grep -i mtk

These tests are not perfect — a distribution could have the code built into the kernel rather than as a module — which is why checking the kernel config and the kernel source package for the exact files or commit range is more reliable.

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Risks, tradeoffs and mitigation priority​

Risk profile​

• The vulnerability is a local, kernel‑level use‑after‑free that can produce a kernel panic when a specific driver path is exercised. In typical cloud or server deployments, an attacker needs local access or a path to trigger the relevant driver logic; this makes remote, unauthenticated exploitation unlikely in many setups, but not impossible in specialized scenarios (for example, multi‑tenant appliances where network paths can trigger driver behavior).
• The practical blast radius depends on whether your environment runs the MediaTek WED driver and whether fleet‑wide configuration enables WED. Some organizations will be entirely unaffected because their kernels do not include the mtk_wed driver or they don’t operate on MT798X hardware. Others (notably edge deployments, IoT, or specialized gateway hardware) may be more exposed.

Prioritization guidance​

• High priority: Azure Linux hosts and any Microsoft‑distributed images that are attested as affected. Patch these first.
• Medium priority: Any Microsoft‑supplied kernel artifacts where the vendor has not yet published an attestation but that are plausible carriers (linux‑azure kernels, WSL2 kernels, Marketplace images). Perform artifact checks and remediate as required.
• Lower priority: Hosts whose kernels lack the MediaTek drivers or environments where WED is not present or is disabled.

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Why vendor attestations like Microsoft’s VEX matter — and their limits​

Machine‑readable attestations (CSAF/VEX) are a major operational improvement for defenders: they let automation quickly triage which products are known affected, fixed, not affected, or under investigation. Microsoft’s October 2025 rollout of VEX for Azure Linux is a meaningful step towards that automation and should reduce noisy alerts where an upstream CVE is irrelevant to your specific product image.
But a few impo

• VEX files are only as useful as the product inventories they annotate. If a product isn’t yet scanned and attested, you must still perform artifact checks.
• VEX/CSAF clarifies exploitability status but does not replace artifact inspection for organization‑specific builds or custom images.
• Vendors may publish VEX at different speeds; a phased rollout means timelines vary by vendor and product family.

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Conclusion​

Microsoft’s advisory that Azure Linux includes the open‑source component implicated by CVE‑2024‑44997 is authoritative and should be treated as a direct, actionable signal for customers running Azure Linux. That said, it is not a categorical guarantee that other Microsoft products are unaffected — it’s a product‑scoped attestation, and Microsoft has said it will expand machine‑readable VEX/CSAF attestations and update CVE mappings if further Microsoft artifacts are found to ship the same upstream component. Operators running non‑Azure Linux Microsoft artifacts must therefore verify artifact contents (or wait for a formal VEX/CSAF attestation) before concluding they are unaffected.
Action checklist (short):

• If you run Azure Linux: apply the vendor update now.
• If you run other Microsoft‑distributed kernels or images: inspect the kernel config, search for mtk_wed or related MediaTek driver files, and consult Microsoft’s VEX/CSAF feed for new attestations.
• If you manage devices with MediaTek MT798X hardware: prioritize testing and patching in your lab and fleet.

For teams that want hands‑on assistance, I recommend exporting a small artifact inventory (kernel versions and package names) and running the quick detection checklist above across a representative sample of your fleet — if you share that inventory I can draft a concise script and a prioritized remediation plan to accelerate triage.

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Source: MSRC Security Update Guide - Microsoft Security Response Center