The Linux kernel vulnerability tracked as CVE-2025-38348 is a small but meaningful buffer‑overflow in the p54 wireless driver (function p54_rx_eeprom_readback()) that can be triggered by a malicious USB device posing as an Intersil p54 Wi‑Fi interface — and while Microsoft’s MSRC entry explicitly states that Azure Linux includes the implicated open‑source component and is therefore potentially affected, that statement is an authoritative product attestation for Azure Linux only and does not prove that no other Microsoft product or artifact can include the same vulnerable code.
CVE-2025-38348 in plain terms: the vulnerable code path reads an eeprom length value supplied by the device and uses it directly in a memcpy, allowing an attacker who controls the USB device to set the length to a value larger than the destination buffer and copy past the end of priv->eeprom. The issue was reported publicly in mid‑2025 and fixed upstream in the Linux kernel stable trees by ensuring the driver uses a trusted size and validates the incoming length before copying.
The vulnerability’s practical attack vector is local: an attacker must be able to connect a malicious USB device (or otherwise cause the host to read faked p54 eeprom data). The most immediate impacts are kernel memory corruption, crashes (OOPS/panic), and — depending on context and exploitation sophistication — potential information disclosure or an escalation primitive; public trackers assign this class of flaw medium‑to‑high severity depending on exploitability scenarios.
Microsoft’s public wording on affected products follows a new, machine‑readable attestation model (CSAF/VEX) the company began rolling out in October 2025. For a given CVE, MSRC’s update‑guide pages frequently include the short product statement you quoted — for example, “Azure Linux includes this open‑source library and is therefore potentially affected.” That sentence is a concise inventory attestation: Microsoft has inspected the Azure Linux artifacts, found the upstream component that maps to the CVE, and therefore lists Azure Linux as a confirmed remediation target. It is not an automatic declaration about the rest of Microsoft’s product portfolio.
Positive‑tech/security vendor writeups and distro advisories also list affected kernels and confirm that the exploit path requires local USB device interaction; they recommend applying upstream vendor kernel updates or distribution kernel packages that include the fix. Where vendors provided CVSS scores, they generally put this issue in the medium‑to‑high range depending on assumptions about local access and host configuration.
If you need the most authoritative technical artifacts for triage (the actual kernel commits and stable-tree diffs), consult the kernel stable git commit referenced by the CVE record; OSV and distro trackers include commit references that you can match to the kernel stable branches in your environment. OSV and Debian trackers are useful cross‑commit hashes or distro package names.
Why this mattericrosoft’s attestation is useful because it gives customers an immediate and automated signal for a specific product family (Azure Linux). Customers running those images should prioritize patching them per Microsoft guidance.
Because the p54 code lives in the upstream Linux kernel source, the same file can surface in mu. Prioritize checking the following Microsoft‑distributed artifacts if they are present in your estate:
Source: MSRC Security Update Guide - Microsoft Security Response Center
Background / Overview
CVE-2025-38348 in plain terms: the vulnerable code path reads an eeprom length value supplied by the device and uses it directly in a memcpy, allowing an attacker who controls the USB device to set the length to a value larger than the destination buffer and copy past the end of priv->eeprom. The issue was reported publicly in mid‑2025 and fixed upstream in the Linux kernel stable trees by ensuring the driver uses a trusted size and validates the incoming length before copying.The vulnerability’s practical attack vector is local: an attacker must be able to connect a malicious USB device (or otherwise cause the host to read faked p54 eeprom data). The most immediate impacts are kernel memory corruption, crashes (OOPS/panic), and — depending on context and exploitation sophistication — potential information disclosure or an escalation primitive; public trackers assign this class of flaw medium‑to‑high severity depending on exploitability scenarios.
Microsoft’s public wording on affected products follows a new, machine‑readable attestation model (CSAF/VEX) the company began rolling out in October 2025. For a given CVE, MSRC’s update‑guide pages frequently include the short product statement you quoted — for example, “Azure Linux includes this open‑source library and is therefore potentially affected.” That sentence is a concise inventory attestation: Microsoft has inspected the Azure Linux artifacts, found the upstream component that maps to the CVE, and therefore lists Azure Linux as a confirmed remediation target. It is not an automatic declaration about the rest of Microsoft’s product portfolio.
What the MSRC statement actually means — attestation vs. exclusivity
The narrow, literal reading
When MSRC writes that “Azure Linux includes this open‑source library and is therefore potentially affected,” read it literally:ed inventory work for that product family and found the implicated upstream code in the Azure Linux builds it checked. For Azure Linux customers this is authoritative and actionable guidance: treat those images and kernels as in‑scope and apply the vendor’s remediation guidance.Why that sentence is not a guarantee of exclusivity
Large vendors ship many artifacts — kernels, images, Marketplace appliances, container base images, WSL kernels, device firmware, and more. A single upstream file can appear in many different build outputs depending on:- The exact upstream commit used to build a kernel.
- The kernel configuration flags chosen at compile time (which drivers are built-in, which are modules, and which are omitted).
- Any vendor backports or local patches that either introduced or fixed the code befotse of this, Microsoft’s attestation for one product family (Azure Linux) is a product‑scoped statement. Absence of a similar attestation for Product B is absence of attestation, not proof that Product B is clean. Practical guidance for defenders is to treat Azure Linux as confirmed affected and to verify other Microsoft artifacts in their estate until they are either attested Not Affected or patched.
Cross‑checking the technical facts (what independent sources say)
Multiple independent vulnerability trackers and distribution advisories document the same technical root cause and upstream fix for CVE‑2025‑38348. The National Vulnerability Database (NVD) and OSV/plain CVE records describe the p54_rx_eeprom_readback memcpy of a device‑supplied length; distribution trackers (Debian, SUSE, Ubuntu/USN) and commercial vulnerability databases echo the technical summary and point to the upstream kernel commits that remove the trust from the device‑supplied length and add a safe size into the device context. These independent traces corroborate the basic CVE description and the fix approach.Positive‑tech/security vendor writeups and distro advisories also list affected kernels and confirm that the exploit path requires local USB device interaction; they recommend applying upstream vendor kernel updates or distribution kernel packages that include the fix. Where vendors provided CVSS scores, they generally put this issue in the medium‑to‑high range depending on assumptions about local access and host configuration.
If you need the most authoritative technical artifacts for triage (the actual kernel commits and stable-tree diffs), consult the kernel stable git commit referenced by the CVE record; OSV and distro trackers include commit references that you can match to the kernel stable branches in your environment. OSV and Debian trackers are useful cross‑commit hashes or distro package names.
Is Azure Linux the only Microsoft product that could include the vulnerable p54 code?
Short answer: No — Azure Linux is the only Microsoft product Microsoft hao far) to include the implicated upstream component for CVE‑2025‑38348, but that attestation is product‑scoped and other Microsoft artifacts could still include the same vulnerable upstream code until they are inventory‑checked or attested.Why this mattericrosoft’s attestation is useful because it gives customers an immediate and automated signal for a specific product family (Azure Linux). Customers running those images should prioritize patching them per Microsoft guidance.
- However, many Microsoft artifacts are not the same as Azure Linux images: WSL2 kernels, linux‑azure kernel packages used to back some VM SKUs, curated Marketplace images, AKS node base images, and appliance images can each be built from different upstream snapshots and configurations. Any of those artifacts could includever source unless Microsoft or you verify otherwise.
Because the p54 code lives in the upstream Linux kernel source, the same file can surface in mu. Prioritize checking the following Microsoft‑distributed artifacts if they are present in your estate:
- Azure Linux images and kernel packages (the attested familyhest‑priority remediation targets.
- linux‑azure kernel packages used for certain Azure VM SKUs — separate from the Azure Linux distribution and sometimes built from different upstream snapels Microsoft distributes with Windows or that your organization deploys — WSL kernels are updated independently and can include different kernel configs.e images and partner appliances that derive from Microsoft base images — a vulnerable kernel in a base image can propagate to many derived images.
- AKS/AKS node pools and curated container host images: if you run Linux node images (especially community or Microsoft curated images), verify the kernel build that underpins those nodes.
- Developer machines and CI images supplied by your organization that may embed Microsoft-provided kernels or base images. These oftNote: Presence of the upstream source file in a source tree is not sufficient to declare runtime exposure. For practical vulnerability, the kernel build must have compiled the driver (built‑in or as a module), the module must exist in the shipped artifact, and runtime conditions must allow the driver to be loaded and the vulnerable path exercised. That nuance means your verification must be artifact‑level (binary/module presence and configuration), not just source level.
Concrete detection and verification checklist (repeatable, prioritized)
Below are pragmatic, repeatable checks you can run across hosts, images, and container artifacts to determine if an artifact contains the p54 driver and whether it is potentially vulnerable.- Identify the kernel and build provenance:
- uname -r; cat /proc/version; inspect /boot for the exact packaged kernel image.
- For container images, inspect the image manifest and any SBOM/BOM metadata the publisher exposes.
- Look for the p54 module or driver in module trees:
- On a running host: ls /lib/modules/$(uname -r) | grep -i p54
- modinfo p54 (will show if a module is available)
- If you can boot a representative image or instance, check whether the module is loaded or can be loaded:
- lsmod | grep -i p54 or journalctl -k | grep -i p54
- If you cannot boot the image (for Marketplace or offline images), scan image layers for kernel module tarballs or /lib/modules snapshots in the image filesystem.
- For WSL2 kernels, query the distributed WSL kernel image (on Windows run wsl --status and check the kernel file, or run uname inside WSL after launching the distribution). WSL kernels are separately maintained and may need separate verification.
- If the module exists but you are uncertain about the version/fix, verify the kernel package or module build includes the backport or stable‑tree commit that fixed the memcpy length check (consult distro advisories or kernel commit references). OSV, distro trackers, or the NVD entry include commit references you can check against your kernel package.
- Blacklist the p54 module on hosts that do not require that Wi‑Fi driver: echo "blacklist p54" > /etc/modprobe.d/blacklist-p54.conf and rebuild initramfs if necessary.
- For images that must remain unchanged, ensure USB device policy prevents untrusted USB devices from being attached, or use platform/firmware controls (TPM/USB port lockdown) to reduce the attack surface.
- On laptops and endpoints, consider disabling USB mass‑storage and USB network interfaces via firmware or OS policies when not required.
Strengths and limitations of Microsoft’s VEX/CSAF attestations
Strengths (what Microsoft’s approach helps you do)
- Actionable automation: publishing machine‑readable VEX/CSAF attestations for asy for large customers and vulnerability management tools to automate triage and remediation priority. That reduces noise and speeds patching for a large class of customers who run Azure Linux images.
- **Transparency whertestation explicitly ties upstream CVEs to named Microsoft product artifacts, removing ambiguity for those products and enabling deterministic decisions by SOC and patch teams.
Limitations and operational risks
-ates a blind spot:** because Microsoft is publishing attestations product‑by‑product, early attestations only cover what Microsoft has inventoried so far. That leaves a nontrivial gap for other Microsoft artifacts until those are checked and attested. Administrators who treat an absent attf safety risk missing exposures.- Different artifacts, different build choices: the same upstream code can be compiled differently across kernels (built‑in vs module vs omitted). That variability means artifact‑level verification is unavoidable.
- Supply‑chain propagation: a vulnerable kernel in a base image can quickly propagate is, partner appliances, and CI artifacts. The attestation for a single product (Azure Linux) does not stop that downstream propagation; it only identifies one confirmed carrier.
Recommended remediation and governance steps (practical playbook)
- Immediate (first 24–72 hours)
- Patch any running Azure Linux images or kernels per Microsoft’s update guidance. Azure Linux is the attested carrier; prioritize it.
- If patching will take time, apply temporary mitigations: blacklist the p54 kernel module on hosts that do not need wireless, and block attachment of untrusted USB devices where possible.
- Short term (1–2 weeks)
- Run an artifact sweep across your estate for other Microsoft artifacts that ship Linux kernels (WSL2 kernels, linux‑azure packages, Marketplace images, AKS node images). Use image scanning tools and SBOMs where available.
- Validate module presence and kernel package versions; compare the kernel package and commit hashes to upstream fix commits documented in OSV/distro trackers.
- Medium term (2–8 weeks)
- Integrate Microsoft VEX/CSAF attestations into your vulnerability management workflow to convert Microsoft product attestations into automated triage rules. Use those attestations to reduce false positives, but do not rely on them exclusively — continue artifact checks for any un‑attested Microsoft artifacts.
- Where Microsoft provides Not Affected/FIXED attestations for additional products, update your asset inventory and remediation priorities accordingly.
- Longer term (policy)
- Implement image provenance and SBOM requirements for all images you consume from marketplace or vendor catalog verification part of your CI pipeline so that a vulnerable kernel cannot silently propagate.
- Maintain a whitelist/blacklist policy for kernel modules in sensitive environments where local device attachment is possible.
Final assessment and cautionary notes
- Microsoft’s public statement that “Azure Linux includes this open‑source library and is therefore potentially affected” is accurate, important, and actionable for Azure Linux customers — it is a confirmation that Microsoft inspected that product family and found the implicated upstream component. Treat the attestation as a priority remediation signal.
- That statement is not a universal declaration that no other Microsoft product can include the same upstream code. Any Microsoft artifact that ships a Linux kernel build compiled from a vulnerable upstream snapshot — or that includes a backport or vendor patch that reintroduces the code — could still be a carrier until inventory‑checked and attested. Administrators must therefore perform artifact‑level discovery, scanning, and verification across WSL kernels, linux‑azure kernels, Marketplace images, AKS nodes, and other Microsoft‑provided artifacts they run.
- Where a claim cannot be verified from available attestations or inventories, treat it with caution: the absence of an attestation is not evidence of absence. If you need absolute confirmation for a given Microsoft artifact, either consult Microsoft’s VEX/CSAF attestations (as they expand) or perform your own binary/module inspection and SBOM verification.
Source: MSRC Security Update Guide - Microsoft Security Response Center
