CVE-2024-39494 and Azure Linux Attestation: What It Means for Microsoft Artifacts

Microsoft’s phrasing that “Azure Linux includes this open‑source library and is therefore potentially affected” is accurate — it is an authoritative, product‑level attestation for Azure Linux — but it is not a categorical guarantee that no other Microsoft product or artifact can contain the same vulnerable code implicated by CVE‑2024‑39494.

Background / Overview​

CVE‑2024‑39494 is a Linux kernel vulnerability that affects the Integrity Measurement Architecture (IMA). The bug is a use‑after‑free rooted in how a dentry’s name pointer (d_name.name) can change during a rename operation; code paths that read the name without taking a stable snapshot can observe a freed string, producing a use‑after‑free condition. The issue was fixed upstream by taking a stable copy of the name at the call sites.
Microsoft’s Security Response Center (MSRC) has published a short attestation for this and many similar third‑party CVEs saying that the Azure Linux distribution (the distro Microsoft maintains for Azure images and formerly known as CBL‑Mariner) “includes this open‑source library and is therefore potentially affected,” and that Microsoft will publish machine‑readable CSAF/VEX attestations and update CVE records if additional Microsoft products are later identified as carriers. That VEX/CSAF program was publicly launched in October 2025.
This article explains the technical scope of CVE‑2024‑39494, parses the meaning and limits of Microsoft’s Azure Linux attestation, assesses the real operational risk to other Microsoft artifacts, and lays out practical verification and mitigation steps for administrators and security teams.

---

What CVE‑2024‑39494 actually is​

The technical root cause​

At a low level, CVE‑2024‑39494 touches the Linux VFS/dentry naming semantics used by the IMA subsystem. Dentries represent directory entries in the kernel and carry a pointer to the filename string via d_name.name. Under certain race conditions — notably when a rename is in progress — the pointer value can change and the previous string can be freed while another code path still holds the old pointer. Code that dereferences the old pointer without stabilizing the name may experience a use‑after‑free, potentially leading to memory corruption, kernel crashes, or privilege escalation depending on exploitability in a given configuration. Upstream maintainers fixed the bug by ensuring a stable snapshot of the name is taken at the vulnerable call sites.

Affected kernels and distributions​

Upstream advisories and vulnerability databases list a set of kernel ranges that were affected prior to the upstream patch. Distribution vendors subsequently shipped fixes by backporting or upgrading kernel packages. Public vulnerability trackers and security vendors note that the issue appears across various mainstream kernels and has been patched in vendor kernels and popular distributions. Administrators should assume kernels within the reported vulnerable ranges are in scope until confirmed patched.

---

Microsoft’s wording: product attestation versus exclusivity​

What Microsoft actually said​

MSRC’s public guidance for a number of third‑party CVEs uses a consistent phrasing: “Azure Linux includes this open‑source library and is therefore potentially affected.” Microsoft has additionally committed to publishing machine‑readable CSAF (Common Security Advisory Framework) and VEX (Vulnerability Exploitability eXchange) artifacts to commtatus in a machine‑actionable way. That VEX initiative began with Azure Linux in October 2025 as a deliberate phased rollout.

How to read “refore potentially affected”​

• The phrase is an inventory attestation: Microsoft ux builds and found the upstream component present, so the product family is listed as potentially affected and prioritized for remediation.
• The statement is not a technical proof that no other Microsoft product ships the same upstream source or compiled artifact. Microsoft’s attestation is deliberately scoped to the product it names, and the company has said it will update VEX/CSAF records if audits find other affected Microsoft artifacts.
• In short: authoritative for Azure Linux, not exclusive for Microsoft at large.

This distinction matters because Microsoft ships many artifacts — kernels for WSL, linux‑azure builds container base layers, embedded appliances, and service agents — and the presence of a given upstream source file depends on build choices and kernel configuration flags for each artifact.

---

Why Azure Linux being attesr Microsoft products are safe​

Technical reasons: kernels are built, not copied​

Whether an artifact contains a particular upstream kernel file or compiled module depends on at least three technical factors:

• Kernel version an products may use different upstream commit ranges or backported fixes. A vulnerable commit present in one kernel might be absent from another that backported the fix or used a different release.
• Kernel configuration (CONFIG_* flags): many kernel subsystems and drivers are enabled or disabled at build time. A product’s kernel may exclude the IMA subsystem or compile it as a module — affecting presence and exposure.
• Packaging and image composition: some Microsoft artifacts reuse a generic kernel binary; others build specialized kernels for performance, size, or certification reasons. These choices change the final artifact’s attack surface.

Because of these variables, a single upstream CVE can simultaneously be relevant to one Microsoft product while being irrelevant to another — or relevant to both, depending oOperational reasons: phased inventory and transparency
Microsoft adopted a phased rollout for its CSAF/VEX program, starting with Azure Linux. That means the company first focused inventory and attestation work on that product family and will expand to other product families over time. Absence of an attestation for other products therefore reflects the current state of Microsoft’s inventorying effort — not a conclusion about absence of the vulnerable component. Microsoft explicitly said it will update CVE entries if additional Microsoft products are found to include the implicated open‑source component.

---

Cross‑checking the claim: independent sources and community analysis​

Multiple independent vulnerability trackers and security vendors document CVE‑2024‑39494 and its fix in the Linux kernel. The NVD entry summarizes the patch rationale and the technical details of the dentry/dname use‑after‑free, while other advisories document the distribution‑specific kernel ranges and remediation status. These sources confirm the technical facts Microsoft’s attestation concerns; they do not contradict Microsoft’s choice to list Azure Linux as a potentially affected Microsoft product.
Security community coverage and vendor analyses repeatedly interpret Microsoft’s Azure Linux statement as a product‑scoped inventory attestation rather than an exclusivity claim. Community posts and analysis threads emphasize that administrators should treat Azure Linux as a confirmed carrier and independently verify other Microsoft artifacts in their environments.

---

Practical implications: Which Microsausibly carry the vulnerable code?​

The following Microsoft artifacts are the primary candidates that could — depending on build/version/configuration choices — include the same upstream IMA code and therefore be potentially affected:

• Azure Linux (attested): confirmed as a carrier by Microsoft’s inventory work. This is the highest‑confidence “yes.”
• linux‑azure kernel builds used for some Azure Varate kernel build pipelines and may or may not carry the same commits. Verification required.
• WSL2/WSL kernels distributed by Microsoft: historically Microsoft has shipped a WSL kernel binary built from upstream sources; whether any given WSL kernel contains an affected commit depends on the specific kernel revision Microsoft used.
• Marketplace VM images, container base images, and management/agent images: if they include a Linux kernel or a userland package built against a vulnerable kernel, they may be in scope; presence is artifact‑specific.
• Managed appliances Microsoft packages a Linux kernel for device delivery: these can contain upstream code depending on vendor contract and build choices.

None of the above is a categorical list of affected products — each artifact must be verified. The important operational point is that absence of public attestation ≠ absence of exposure.

---

How to verify — checklist for security teams​

If you operate Microsoft‑provided artifacts, follow a short verification playbook:

• Inventory the artifacts you run that contain or reference a Linux kernel (Azure VM images, WSL kernels distributed to endpoints, container base layers, managed node images).
• For each artifact, identify the kernel version and the exact upstream commit range or vendor patch level. This is usually available via kernel version strings, image metadata, package metadata, or by extracting the kernel binary and checking its build ID.
• Map the kernel version/commit to the CVE‑2024‑39494 affected ranges documented by upstream and distribution advisories. Use vendor advisories and NVD as references to determine whether that kernel includes the vulnerable code.
• If the artifact’s kernel is in an affected range, apply vendor or distribution patches promptly. Microsoft has signaled Azure Linux will be patched; for other artifacts, follow vendor guidance or apply kernel updates.
• Where you cannot patch immediately, apply compensating controls: reduce attack surface (limit local access), enable kernel hardening features, and monitor for suspicious kernel oops/panic patterns in telemetry.

These steps expose the operational truth: verification is artifact‑specific and actionable.

---

Recommendations for Microsoft customers and partners​

• Treat Microsoft’s Azure Linux attestation as a high‑priority operational signal: if you run Azure Linux images, follow Microsoft’s remediation guidance immediately. The attestation is a confirmed inventory result for that product.
• Do not assume other Microsoft artifacts are safe. If you run WSL, custom Azure Marketplace images, container base images, or other Microsoft‑supplied binaries that include a Linux kernel, validate those artifacts using the checklist above. Microsoft’s phased VEX rollout means attestations will expand over time; until then perform local verification.
• For enterprise incident response teams: prioritize artifacts by exposure and privilege. A vulnerable kernel on a public‑facing VM matters more than the same kernel in a sandboxed developer environment.
• Keep an eye on Microsoft’s CSAF/VEX feed for updates: MSRC has committed to update CVE records if additional Microsoft products are identified as carriers, and that feed is the canonical machine‑readable signal for changes in Microsoft’s inventory status. ([//www.microsoft.com/en-us/msrc/blog/2025/10/toward-greater-transparency-machine-readable-vulnerability-exploitability-xchange-for-azure-linux)

---

Risk analysis — exploitability and impact​

Exploitability​

From a technical perspective, a use‑after‑free in kernel space can have high impact: kernel memory corruption can lead to crashes (denial of service), information disclosure, or privilege escalation depending on the surrounding code and attacker capabilities. However, successful exploitation depends on local access, kernel configuration, and the presence of other mitigations (KASLR, SMEP/SMAP, kernel lockdown features). Public advisories rate CVE‑2024‑39494 as a meaningful risk that was fixed upstream and backported by distributors.

Impact to Microsoft customers​

• Azure Linux customers should assume the highest urgency: Microsoft’s attestation signals confirmed presence and patching commitments.
• Customers running other Microsoft artifacts should assess exposure via the artifact verification checklist. The probability that other artifacts are affected is non‑zero but artifact‑dependent.
• For large enterprise fleets that mix Microsoft artifacts, the operational burden falls on patch management, image rebuilds, and verifying that the precise kernel versions in production have been updated.

Supply‑chain perspective​

This CVE and Microsoft’s response highlight a broader industry trend: vendors are moving to machine‑readable attestations (CSAF/VEX) to communicate per‑product vulnerability status. That transparency is valuable but — especially during early rollouts — it must be interpreted as a snapshot of inventory coverage rather than a completeness guarantee. Attackers can still seek vulnerable artifacts in other images, so defenders need artifact‑level verification as a best practice.

---

What Microsoft’s statement does — and does not — accomplish​

What the Azure Linux attestation accomplishes:

• Provides a clear, actionabnux customers that a known vulnerable upstream component is present and should be patched.
• Delivers machine‑readable VEX/CSAF artifacts (as part of Microsoft’s phased program) to support automation and faster triage for affected customers and security tools.

What the attestation does not accomplish:

• It does not prove that Azure Linux is the only Microsoft product carrying the vulnerable code. The company has not claimed exclusivity; it has stated a procedural commitment to expand attestations and update CVE records if other products are found to be carriers.
• It does not relieve customers of the responsibility to inventory and verify other Microsoft artifacts in their estate.

---

Verdict: a concise answer to the user’s question​

• Is Azure Linux the only Microsoft product that includes this open‑source library and is therefore potentially affected by CVE‑2024‑39494?

Short, operational answer: No — not necessarily. Azure Linux is the only Microsoft product Microsoft has publicly attested so far to include the implicated upstream code for this CVE, but Microsoft’s attestation is product‑scoped and explicitly procedural: it confirms Azure Linux but does not assert exclusivity. Other Microsoft artifacts could include the same vulnerable code depending on kernel version, build, and configuration; absence of a public VEX/CSAF attestation for those artifacts should be treated as “not yet verified” rather than “not affected.”

---

Final recommendations (action checklist)​

• For Azure Linux customers:
• Apply Microsoft’s recommended updates for Azure Linux immediately. The product is a confirmed carrier and will receive VEX/CSAF updates.
• Validate patched image versions in your deployment pipelines and rebuild any custom images that were derived from affected Azure Linux snapshots.
• For organizations running other Microsoft artifacts:
• Perform an artifact inventory: identify kernels and images that may carry vulnerable code.
• Map kernel versions and build IDs to the affected ranges for CVE‑2024‑39494 using vendor advisories and NVD/third‑party databases.
• Patch or rebuild images as required; where patching is not immediately possible, apply compensating controls and heightened telemetry for kernel oops/panic indicators.
• For security tooling and SOC teams:
• Consume Microsoft’s CSAF/VEX feed as it lands for automated updates; but do not treat early VEX coverage as comprehensive across all Microsoft artifacts.
• Combine VEX data with internal artifact scanning and SBOM/data sources to reach an accurate risk posture.

---

Conclusion​

Microsoft’s MSRC message that “Azure Linux includes this open‑source library and is therefore potentially affected” is accurate and important: it confirms Azure Linux as a verified carrier of the upstream component implicated by CVE‑2024‑39494 and marks that product for prioritized remediation. However, the statement is intentionally scoped — it is a product attestation, not a declaration of exclusivity across all Microsoft products. The correct operational posture for defenders is to treat Azure Linux as a confirmed “yes,” to verify other Microsoft artifacts in their environments on an artifact‑by‑artifact basis, and to use Microsoft’s emerging CSAF/VEX feed as a complementary source rather than a single definitive inventory.
By combining Microsoft’s attestation with independent vulnerability databases and local artifact verification, organizations can convert the VEX signal into precise remediation steps and maintain a defensible, auditable patching stance against CVE‑2024‑39494 and similar supply‑chain vulnerabilities.

---

Source: MSRC Security Update Guide - Microsoft Security Response Center