Azure Linux Confirmed Carrier for CVE-2025-23157, Not the Only Microsoft Risk

The short answer is: No — Azure Linux is not necessarily the only Microsoft product that could include the vulnerable open‑source code, but it is the only Microsoft product Microsoft has publicly attested to include that component so far. Microsoft’s public wording is an explicit, product‑scoped inventory statement for Azure Linux; it is not a categorical technical guarantee that other Microsoft‑distributed kernels, images, or artifacts cannot contain the same upstream Linux kernel code. /archive.ph/2025.12.07-213431/https%3A/msrc.microsoft.com/update-guide/vulnerability/CVE-2024-40999)

Background / Overview​

CVE‑2025‑23157 is an out‑of‑bounds read in the Linux kernel’s Qualcomm Venus video driver — specifically, an issue in the HFI (Host Firmware Interface) parser where repeated or malformed firmware payloads can cause a codec counter to exceed its maximum and thereby trigger an OOB read in init_codecs. Upstream kernel maintainers published patches to reset counters and to make parsing defensive, and the vulnerability was recorded across common vulnerability databases.
Technically, this is a local, low‑to‑medium severity kernel robustness bug: the exploitation vector requires local access to a system that exposes the affected driver (generally devices running Qualcomm multimedia stacks), and the realistic impact is denial‑of‑service (kernel crash) in many configurations. Vendor trackers and distribution advisories classify it accordingly and have published fixes and upgraded kernel packages.
Why this matters to enterprises: the Linux kernel is reused across many products and packaging channels. A vulnerability that lives in an upstream driver will appear in any binary that (a) is built from an upstream commit that contained the offending code and (b) includes the driver in the build (either built‑in or as a module). That makes product‑level attestations useful but not exhaustive: they confirm “this product contains it,” not “only this product contains it.”

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What Microsoft actually said — and how to read it​

Microsoft’s Security Response Guide wording that you quoted is consistent with the company’s recent practice: when Microsoft discovers that an upstream open‑source component appears in a specific Microsoft product, the MSRC record will state that product name and note that Microsoft will update the CVE mapping if additional Microsoft products are identified later. That phrasing establishes Azure Linux as a confirmed carrier for the vulnerable code and signals that Azure Linux customers should prioritize remediation.
Important clarifications about the wording:

• “Includes and therefore potentially affected” is an attestation for the named product only. It tells you Microsoft has inspected that product and found the component there. It does not assert exclusivity.
• Absence of other product names is not proof of absence. Microsoft explicitly commits to updating its CSAF/VEX attestations when it discovers other products that ship the same component; until that updaifacts should not be assumed safe.
• Practical takeaway: Treat the Azure Linux attestation as a definitive remediation signal for Azure Linux — and treat other Microsoft‑delivered kernels or images as unverified until you verify them yourself or Microsoft updates the attestation.

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Which Microsoft products could include the same vulnerable code?​

From a technical perspective, any Microsoft artifact that ships a Linux kernel build containing the upstream Venus driver subtree could also include the vulnerable code — provided the driver is present in the build and enabled at compile time or shipped as a module. The most plausible Microsoft carriers are:

• Azure Linux images (confirmed). Microsoft attested Azure Linux specifically; Azure Linux images therefore are confirmed targets for remediation.
• WSL2 (Windows Subsystem for Linux) kernel images distributed by Microsoft. WSL2 ships a Microsoft‑built Linux kernel and publishes its source tree. Whether a given WSL kernel build includes the Qualcomm Venus code depends on the kernel version and the build configuration used by Microsoft for that WSL release. You must check your WSL kernel build and config to be sure.
• Microsoft‑published kernels used in Azure VM SKUs (linux‑azure / “azure‑tuned” kernels). Some Azure images use kernels that Microsoft publishes or “azure‑tunes.” Those kernels can include upstream driver code; distribution advisories and OSV entries document how cloud kernels map to CVE ranges.
• Azure Marketplace / third‑party images running on Microsoft infrastructure. These are frequently built by vendors (Canonical, Red Hat, SUSE, ISVs) and may include the upst— not Microsoft — typically carries responsibility for patches to their images. However, the fact that the image runs on Azure does not make Microsoft’s Azure Linux attestation cover those images.
• Other Microsoft artifacts that distribute Linux kernels (managed node images, container host images, specialized devices). Any Microsoft‑packaged kernel binary or module set is a candidate carrier until verified.

In short: Azure Linux is the confirmed carrier; other Microsoft artifacts may be carriers depending on kernel version and build configuration — you must verify each artifact you run.

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How to verify whether your Microsoft‑supplied artifact is affected​

Use the following practical, verifiable steps. These are ordered so you can triage quickly and escalate to remediation when necessary.

1) Confirm whether you run Azure Linux images​

• If you run Azure Linux (Microsoft’s distro), treat the attestation as a confirmed hit and follow Microsoft’s published patch guidance immediately. Microsoft’s CSAF/VEX attestation gives you a machine‑readable inventory claim you can consume.

2) Check the kernel version and compare it to the vulnerability’s affected ranges​

• On the target machine (Azure VM, WSL, container host), run:
• uname -r
• Compare the kernel release against published affected version ranges. Public vulnerability trackers (NVD, OSV/CVE feeds) list the ranges and CPEs for CVE‑2025‑23157. If your kernel falls in an affected range, you should treat the artifact as potentially vulnerable until patched.

3) Inspect the kernel build and configuration for driver presence​

• Look for the driver source or module:
• Check /lib/modules/$(uname -r)/ for a venus module or for qcom/venus files.
• On systems that expose kernel config, check /proc/config.gz or /boot/config-$(uname -r) for CONFIG options that enable the driver (search for qcom, VENUS, or other platform flags).
• For WSL2, Microsoft ships kernel sources and the binary; you can:
• In the WSL shell, run uname -r then examine the corresponding WSL kernel repository tag on microsoft/WSL2-Linux-Kernel to see whether the upstream tree and config would include the venus code. WSL kernels are maintained and updated via Microsoft Update, so the build you run will reflect whatever config Microsoft used.

4) Inspect modules shipped in WSL’s modules.vhdx or other vendor module packages​

• Newer WSL2 releases distribute modules in a modules.vhdx shipped alongside bzImage. Mount that VHDX and examine its /lib/modules/$(uname -r) contents for the suspect driver. If the driver is absent, WSL is unlikely to be affected in that build.

5) If you manage image pipelines (Marketplace, Azure image builders)​

• Inspect the kernel package installed in the image (linux‑azure, linux‑image‑*). Cross‑check those kernel package names against OSV, NVD, and vendor advisories to see whether the kernel version was patched. Ubuntu/Canonical advisories often publish specific package names that fix the CVE; use those package names to match your image contents.

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Recommended remediation and mitigation steps​

• Patch promptly. Apply vendor kernel updates as soon as Microsoft or the relevant distribution announces a fix for the affected kernel version on your platform. Major Linux distros and cloud vendors published patched package versions shortly after the CVE was assigned.
• For Azure Linux customers: follow the MSRC guidance and CSAF/VEX output for the specific Azure Linux SKU you run. The MSRC attestatft will update the CVE/VEX mapping if more products are identified; keep subscribed to those updates.
• For WSL2 users: ensure your Windows installation has received the latest WSL kernel update via Windows Update, or manually switch to a patched kernel image if you manage custom kernels. Inspect the WSL kernel tag and modules.vhdx if you need to verify specific module content.
• Inventory and detection: run the detection checklist across all Microsoft‑issued artifacts you operate (Azure images, WSL, Marketplace images). Use host inventory tools to check kernel versions and to look for the presence of the qcom Venus driver code. If you cannot patch immediately, consider isolating affected systems and restricting local user access where feasible.
• Supply‑chain diligence: do not rely solely on an initial product list when a kernel vulnerability is disclosed. Build processes, CONFIG flags, and backports determine exposure. Implement an artifact‑level verification process (SBOMs, VEX/CSAF consumption, or direct binary inspection) for Microsoft‑distributed kernels in your environment.

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How confident can you be that other Microsoft products are safe?​

You can only be certain by performing an artifact‑level verification. Microsoft’s attestation for Azure Linux is trustworthy for that product family: it is a published inventory result and should be used by Azure Linux customers to prioritize patching. However:

• Microsoft’s attestation does not guarantee other Microsoft‑supplied kernels are free of the code; other kernels may or may not include the driver depending on kernel version and build configuration.
• The correct operational posture is conservative: treat other Microsoft kernels (WSL, linux‑azure, Marketplace kernels) as potentially affected until verified rather than assuming they are safe simply because Microsoft has not yet named them in the CVE mapping.

If you need to be absolutely certain for regulatory, compliance, or high‑assurance reasons, verify each kernel binary you operate by checking kernel configs and module lists against the known affected commits and the published fixed commits referenced in public advisories. Public trackers list the upstream fixes and affected commits; use those commit signatures and CPE ranges as a basis for verification.

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Sources, verification notes, and caveats​

• The technical description and upstream fix history for CVE‑2025‑23157 are recorded in mainstream vulnerability trackers and the upstream kernel changelogs; NVD and OSV entries summarize the vulnerability and link to the stable kernel patches. These authoritative trackers also list affected kernel ranges and CVSS guidance.
• Distribution advisories (Ubuntu, Debian, Oracle) and independent security vendors published package‑level fixes; those advisories are the operational source you should consult to get package names and upgrade commands for specific distros and cloud images.
• Microsoft’s Security Update Guide pages and CSAF/VEX attestations state that Azure Linux includes the implicated open‑source component and that Microsoft will add additional product attestations if more Microsoft products are identified. That statement is an authoritative attestation for Azure Linux — and it is intentionally scoped.
• WindowsForum community postings and technical explainers (internal audit threads) have highlighted the same nuance: product naming in an advisory is a confirmation for the named product, not an exclusivity guarantee, and defenders should inventory all Microsoft‑distributed kernels in their estate. These collected community analyses and inventories are useful operational guidance; they reiterate the verification steps in this article.

Caveats and unverifiable claims

• I do not and cannot assert that specific Microsoft artifacts beyond Azure Linux are affected unless Microsoft or the artifact’s publisher has published a matching attestation or you (the operator) have inspected the artifact and found the vulnerable code. If you need a definitive answer for a specific image (for example: “Is Windows build X’s WSL kernel release tag linux-msft-wsl-6.6.36.3‑XX affected?”), the correct method is to inspect that kernel tag, the kernel config used, and the modules shipped with that release. The MSRC attestation and upstream advisories provide the references you need to do that verification.

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Practical checklist (summary — what to do next)​

• If you run Azure Linux, prioritize patching per Microsoft’s guidance immediately.
• Inventory all Microsoft‑distributed kernel artifacts you run (WSL2, linux‑azure kernels, Marketplace images).
• For each artifact, check: uname -r, /proc/config.gz (or vendor kernel config), and /lib/modules/$(uname -r) for the presence of Venus / qcom drivers. If present and the kernel version is in the affected range, patch.
• Monitor MSRC CSAF/VEX feeds for updates — Microsoft will publish additional attestations if they identify other products as carriers.
• If you cannot patch immediately, implement containment: restrict local user access, limit untrusted code execution on affected hosts, and apply host‑level detection rules that look for suspicious use of the affected driver.

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Conclusion
Microsoft’s short, public answer — that Azure Linux includes the implicated open‑source library and is therefore potentially affected — is accurate and operationally useful: it names a confirmed carrier and gives Azure Linux customers a clear remediation signal. However, from a technical and supply‑chain perspective, that sentence is not an exclusive guarantee. Any Microsoft‑distributed kernel binary or image built from an upstream tree that included the Venus driver (and whose kernel configuration enables or ships that driver) could likewise be affected until verified and patched. Defenders should therefore use Microsoft’s attestation as an immediate priority list for Azure Linux while simultaneously inventorying and verifying other Microsoft kernels (WSL, linux‑azure, Marketplace images, etc.) using the concrete steps above.
If you want, the next step is to supply the kernel release strings or image names for the Microsoft artifacts in your environment (WSL uname -r, Azure image SKU, or marketplace image names). With those exact artifact identifiers I can map them against the published affected kernel ranges and provide a short list of which artifacts are likely in scope and what specific package updates to apply.

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Source: MSRC Security Update Guide - Microsoft Security Response Center