Azure Linux CVE-2025-37771: Attestation Limits Across Microsoft Products

Microsoft’s brief public mapping for CVE-2025-37771—“Azure Linux includes this open‑source library and is therefore potentially affected”—is accurate for the product Microsoft has inspected, but it is not a categorical guarantee that no other Microsoft product or kernel image could include the same vulnerable upstream Linux code.

Background / Overview​

CVE-2025-37771 is a Linux-kernel robustness bug fixed in the AMD DRM power-management code (drm/amd/pm). The defect allows a user-settable speed value to reach a magnitude that triggers a division-by-zero condition when the driver computes a derived value; the problem was reported by the Linux Verification Center and fixed in upstream stable kernel trees. The vulnerability is classified as an availability-focused kernel robustness issue (local, non‑remote exploit), and has been mapped into multiple distribution advisories.
Microsoft’s Security Response Center (MSRC) has joined other vendors in publishing machine-readable attestations for third‑party/open‑source vulnerabilities via CSAF/VEX, and in that program Microsoft has started with the Azure Linux distribution (the product family formerly marketed internally as CBL‑Mariner). In plain terms MSRC can now say, in a machine-consumable way, which Microsoft product artifacts it has surveyed and whether those artifacts are “Known Affected,” “Not Affected,” “Under Investigation,” or “Fixed.” That rollout began publicly in October 2025.
Microsoft’s one-line CVE mapping you quoted reflects this phased, product‑by‑product approach: Azure L product the company has inventory-checked and thus the product MSRC can confidently label as “potentially affected” for the CVE in question. Microsoft has also stated it will update CVE/VEX records as additional products are identified.

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What “Azure Linux includes this open‑source library and is therefore potentially affected” actually means​

• It is an authoritative, product‑scoped inventory statement. Microsoft has inspected the Azure Linux build artifacts (kernel packages, images, or both) and located the upstream component that contained the vulnerable drm/amd/pm code. That is why Azure Linux is listed as “potentially affected” for thisEX/CSAF data.
• It is not an exclusivity claim. The statement does not assert that other Microsoft products cann same upstream source files or compiled drivers. Microsoft’s VEX rollout is intentionally phased and currently focused on Azure Linux; absence of a VEX entry for another product is not forensic proof that the product is safe.
• Whether another Microsoft product is actually vulnerable depends on per‑artifact build configuration and shipping choices: a kernel source tree can contain many drivers; whether a distributed kernel or appliance binary includes and enables the offending code is an artifact-by-artifact question.

These distinctions—attestation versus exclusivity, source presence versus compiled-in module—are the technical heart of why Azure Linux being named does not automatically absolve or condemn other Microsoft products.

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Why Azure Linux is the only Microsoft product MSRC can currently name (but not necessarily the only carrier)​

Microsoft’s VEX/CSAF rollout is a deliberate, incremental program that starts with a single product (Azure Linux) and expands outward. Because the VEX statements are generated from Microsoft’s artifact inventory work, MSRC can truthfully say that Azure Linux includes the upstream component. For other Microsoft products (for example, the WSL2 kernel image, linux-azure packages used in some VM SKUs, Marketplace images, appliance binaries, or partner-curated images), Microsoft either has not yet completed artifact-level inventory work or has not yet published the corresponding VEX statement. Until MSRC publishes that attestation, it cannot assert “Known Affected” or “Not Affected” for those artifacts with the same level of machine-readable certainty.
Multiple independent vulnerability trackers and distribution advisories list CVE-2025-37771 and point to kernel commits and distribution fixes; those sources corroborate the technical nature and the fix. They also show how vendors map upstream kernel fixes into their own kernels and advisories—an exercise that is independent of Microsoft’s VEX attestation but convergent on the same technical change.

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Could other Microsoft products include the same vulnerable library?​

Short answer: Yes — it is possible and, in some cases, plausible. But it is not automatically true for every Microsoft product.
Longer, technical explanation:

• Microsoft distributes multiple, distinct Linux kernel artifacts across its ecosystem:
• Azure Linux distributions and kernel packages (the attested artifacts).
• The WSL2 kernel binary and source trees published for Windows Subsystem for Linux.
• linux-azure kernel packages that may be used in certain Azure VM SKUs.
• Marketplace VM images and partner appliance images that contain their own kernel builds.
  -ilds for container hosts or edge devices that Microsoft or partners ship.
  Each of these is a separate artifact that may or may not include the AMD DRM driver tree or enable the specific drm/amd/pm code path in the build configuration.
• Inclusion ≠ enabled:
• The upstream Linux source tree contains many drivers by default, but kernel build configuration (CONFIG_* opon policy determine whether a driver is built into the kernel, compiled as a module, or omitted entirely.
• A product might include the source files in its repository but compile them out of the delivered binary. Only compiled artifacts matter for practical exposure.
• WSL and GPU support:
• WSL2 has evolved to include GPU capabilities on Windows hosts; Microsoft maintains a WSL kernel build. Whether that kernel has the vulnerable drm/amd/pm code compiled and enabled depends on the specific WSL kernel configuration. MSRC’s Azure Linux attestation tells you nothing directly about WSL unless MSRC publishes a WSL-specific VEX entry.

Because of these differences, it is technically correct to treat Azure Linux as a confirmed carrier (and to take remediation action there), while simultaneously refusing to assume that other Microsoft artifacts are unaffected without either per-artifact inspection or an explicit VEX attestation from Microsoft.

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Practical advice for customers and operators: how to verify exposure in Microsoft-supplied artifacts​

If you run Microsoft-supplied Linux artifacts (Azure Marketplace images, WSL2 instances, Azure VMs, AKS node images, or any Microsoft‑distributed VM images), you should treat the MSRC statement as actionable for Azure Linux and as a prompt to verify other artifacts in your environment. Below are practical, concrete steps to verify whether a particular running system contains the vulnerable driver or path.

• Identify the kernel and build artifacts
• Check the kernel version: uname -a
• Inspect the installed kernel package or artifact name (for Azure Linux this will often be azl3/azl2 kernel names).
• Recognize that product naming and kernel package names matter when mapping to VEX/CSAF attestation entries.
• Check whether the AMD GPU driver code is present and enabled
• Check for a kernel config file:
• cat /pr | grep -E 'AMDGPU|DRM|CONFIG_DRM' (or look in /boot/config-$(uname -r) if present)
• If CONFIG_AMDGPU is enabled as =y or =m, the driver is present in the running kernel or as a module:
• zcat /proc/config.gz | grep CONFIG_AMDGPU
• Confirm whether the module is loaded:
• lsmod | grep amdgpu
• Check module files:
• modinfo amdgpu (if present)
  These checks show whether the binary delivered to your host actually includes and exposes the driver. Presence of the driver as a module or built-in is what matters for exposure, not merely the upstream source tree presence.
• If you manage many images or a cloud estate, automate the checks
• Use configuration management tools (Ansible, Chef, Puppet) or an inventory scanner that collects kernel config data and loaded module information across your fleet.
• In Azure, use scheduled runbooks or guest configuration policies to gather /proc/config.gz and lsmod output from VM fleets and report artifacts that enable the amdgpu driver.
• Review Microsoft VEX/CSAF artifacts for matching CVE entries
• MSRC publishes per‑product VEX JSON that maps CVEs to artifacts; check the published VEX/CSAF entries (the VEX tree for MSRC lists Azure Linux entries first) to see which exact azl kernel versions and artifacts were inspected and what status was assigned. Microsoft has promised to update those entries if additional products are found to be carriers.
• Verify upstream patches and vendor advisories
• Upstream kernel commits and distribution advisories (NVD, distro security advisories, OSV, Debian/Ubuntu advisories) list the exact commits and backport patches that address the defect. Use those references as the canonical fix identifiers when comparing to your kernel versions.

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Immediate mitigations and remediation options​

If you determine a given artifact includes the vulnerable DRM code and that the driver is loaded or could be exercised, you have multiple remediation options. Each option carries trade-offs that must be weighed against operational needs (GPU usage, graphics workloads, VM performance).

• Update / patch
• The cleanest remediation is to install the vendor-supplied kernel update or the distribution security update that includes the upstream fix. Upstream commits have been merged; distributions and vendors (Ubuntu, Oracle, Debian, etc.) have published advisories and packages. For Azure Linux, apply MSRC/azl kernel updates as Microsoft publishes them.
• Blacklist the module (when GPUs are not required)
• If the host does not require AMD GPU functions, you can prevent the amdgpu module from loading:
• echo "blacklist amdgpu" > /etc/modprobe.d/blacklist-amdgpu.conf
• update-initramfs -u (or equivalent per distro)
• Caveat: blacklisting disables AMor workloads that need it (graphics, compute). Evaluate before applying at scale.
• Disable hotspots at boot (advanced)
• Some kernel boot-time options or module parameters can limit driver paths; these are vendor- and driver-specific and should be applied with vendor guidance.
• Compensating controls
• Restrict local unprivileged access to systems that expose kernel device interfaces that might exercise the driver.
• Apply least privilege and runtime restrictions on untrusted containers or workloads on hosts that may hold vulnerable drivers.
• For WSL2 and developer images
• If you use WSL2 and rely on GPU passthrough for compute, verify the WSL kernel configuration and Microsoft’s WSL kernel updates. Do not assume WSL kernels are unaffected; MSRC has not yet attested all Microsoft artifacts.

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Operational guidance for cloud and security teams​

• Treat the MSRC Azure Linux attestation as a confirmed inventory finding for those specific artifacts and prioritize remediation of Azure Linux hosts accordingly. The VEX mapping is intended to reduce ambiguity for that product.
• Do not assume other Microsoft artifacts are safe until they are explicitly attested as Not Affected or Fixed by Microsoft, or until you have inspected the artifact binaries/packaging yourself. The presence/absence of the vulnerable code in other artifacts is an artifact-level question—check the running kernel config and modules.
• For large estates, implement an automated triage pipeline:
• Collect kernel version + kernel config + lsmod for all hosts.
• Match kernel versions against published upstream commit IDs or distribution security advisory patch versions.
• Flag images where CONFIG_AMDGPU is present and the module is loaded or available as a module.
• Watch MSRC VEX/CSAF feeds for updates. Microsoft has committed to expanding VEX coverage beyond Azure Linux; the VEX files are machine-readable and are designed to be ingested by security automation. Until Microsoft publishes an attestation for a product, assume “unknown” and verify.

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Risk analysis: why Microsoft chose this wording and where misunderstandings happen​

• Why the short wording? A compact MSRC product mapping—“Azure Linux includes this open-source library and is therefore potentially affected”—is intentionally concise and machine‑friendly. It is a necessary step so customers can automate decisions without reading long prose describing build trees and module flags. That single-line attestation is authoritative for the checked artifact.
• Where readers misinterpret it: Many people read the line as implying exclusivity (i.e., “only Azure Linux is affected”). That is not what the attestation asserts. Microsoft’s approach reduces noise (it name-checks the attested artifact) but it also requires readers to understand the product-by-product nature of the rollout. Industry commentary and forum explainers have repeatedly highlighted that nuance.
• The technical reason exclusivity cannot be assumed: the upstream Linux source files are reused across many distributions and kernel builds; whether an artifact is truly in-scope depends on per-artifact build configurations and binary contents. This is a general problem across vendors and is exactly why CSAF/VEX exists: to provide machine-readable, per-artifact answers.

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Recommended checklist for Microsoft customers (concise)​

• Priority 1: If you run Azure Linux images, apply the vendor-supplied updates Microsoft publishes against the azl kernel as soon as they are available. MSRC’s attestation is a signal to act on those Azure Linux artifacts first.
• Priority 2: Inventory all Microsoft‑distributed kernel artifacts you rely on (WSL2 kernels, linux-azure, Marketplace images, partner appliances). For each artifact:
• Check /boot/config-$(uname -r) or /proc/config.gz for CONFIG_AMDGPU or equivalent DRM/AMD flags.
• Check lsmod/modinfo for amdgpu presence.
• If present and you cannot immediately patch, consider blacklisting the module if GPU functionality is not required.
• Priority 3: Automate detection via fleet-wide scripts or endpoint management tooling. Create an operational rule that flags any host with CONFIG_AMDGPU set or with the amdgpu module present.
• Priority 4: Subscribe to MSRC VEX/CSAF feeds and distribution security announcements (NVD/OSV/distro advisories) for authoritative fix identifiers and dates. Use those identifiers to match versions to the upstream commit or patched package.

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Conclusions and final assessment​

Microsoft’s MSRC statement that Azure Linux includes the implicated open-source library and is therefore potentially affected is factually correct and important for customers who run Azure Linux; it is the product-level inventory result that Microsoft’s new VEX/CSAF program is designed to produce. However, that statement is not a categorical statement that only Azure Linux could ever include the affected drm/amd/pm code. Other Microsoft artifacts—WSL2 kernels, linux-azure kernels used in certain Azure VM SKUs, Marketplace images and appliance kernels—are separate artifacts that require their own inventory checks or their own VEX attestation from Microsoft before you can claim they are Not Affected.
Operationally: treat Azure Linux as a confirmed carrier and remediate it urgently per vendor guidance. At the same time, treat other Microsoft-supplied artifacts as “unknown” until you either (a) inspect the artifact binary/configuration for the presence of the AMD DRM code and module, or (b) MSRC publishes a VEX attestation for that specific product/artifact. Automate these checks where possible, because kernel-level, configuration-dependent vulnerabilities are exactly the kind of problem that scale tools and VEX/CSAF automation are intended to solve.
If you would like, I can produce a concise runbook with exact commands and an Ansible playbook template to inventory kernels and amdgpu module presence across a fleet of Azure VMs or a mixed environment (WSL, Marketplace images, and Azure Linux).

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Source: MSRC Security Update Guide - Microsoft Security Response Center