Microsoft’s MSRC entry for CVE‑2024‑29195 identifies a buffer‑length validation flaw in the azure‑c‑shared‑utility (the C “shared utility” used by Azure IoT C SDKs) that can lead to an integer wraparound, under‑allocation and heap buffer overflow — and it explicitly notes that Azure Linux includes the implicated open‑source library and is therefore potentially affected. That MSRC attestation is authoritative for Azure Linux, but it is not a technical proof that no other Microsoft product could ship the same vulnerable library; absence of additional attestations is not proof of absence. tps://nvd.nist.gov/vuln/detail/CVE-2024-29195)
This feature unpacks what that MSRC wording actually means, how the vulnerability works and was fixed upstream, which Microsoft artifacts are plausibly at risk beyond Azure Linux, and what defenders and operators should do now to verify exposure and mitigate risk.
CVE‑2024‑29195 is a memory‑safety defect in the azure‑c‑shared‑utility library — a small, portable C library used by the Azure IoT C SDK and related Azure IoT components to handle buffer management, networking adapters and other common helpers. When certain buffer‑length parameters are processed without safe overflow checks, an attacker who can supply specially crafted payloads can trigger an integer wraparound that leads to under‑allocation and a heap buffer overflow. Under the right conditions this can be escalated to remote code execution. The vulnerability has been documented in public vulnerability trackers such as NVD and distribution advisories (Ubuntu, Debian), and multiple security vendors published impact summaries shortly after disclosure.
Technical prerequisites for exploitation are non‑trivial: public advisories note that exploitability requires things like a compromised Azure account to inject malformed messages through IoT Hub, bypassing IoT Hub’s documented 128 KB message payload limit, and the attacker’s ability to overwrite executable memory on the target device. These conditions make real‑world exploitation harder, but not impossible — particularly in device fleets where operators accept messages from diverse, less‑trusted sources or where edge gateways perform message reassembly.
Upstream maintainers implemented a fix that adds explicit, overflow‑aware allocation checks (safe_add / safe_multiply style helpers), and the patch is visible in the azure‑c‑shared‑utility repository as commit 1129147… which adds malloc size checks across affected code paths. Security scanners and vendor advisory pages list the patched commit / fixed release as the remediation. (github.com)
This distinction matters operationally. Azure Linux customers have an immediate, actionable remediation path. Customers running other Microsoft images, appliances or artifacts must treat the MSRC arting point for their own verification steps rather than a blanket clearance for the rest of Microsoft’s catalog.
Source: MSRC Security Update Guide - Microsoft Security Response Center
This feature unpacks what that MSRC wording actually means, how the vulnerability works and was fixed upstream, which Microsoft artifacts are plausibly at risk beyond Azure Linux, and what defenders and operators should do now to verify exposure and mitigate risk.
Background / Overview
CVE‑2024‑29195 is a memory‑safety defect in the azure‑c‑shared‑utility library — a small, portable C library used by the Azure IoT C SDK and related Azure IoT components to handle buffer management, networking adapters and other common helpers. When certain buffer‑length parameters are processed without safe overflow checks, an attacker who can supply specially crafted payloads can trigger an integer wraparound that leads to under‑allocation and a heap buffer overflow. Under the right conditions this can be escalated to remote code execution. The vulnerability has been documented in public vulnerability trackers such as NVD and distribution advisories (Ubuntu, Debian), and multiple security vendors published impact summaries shortly after disclosure.Technical prerequisites for exploitation are non‑trivial: public advisories note that exploitability requires things like a compromised Azure account to inject malformed messages through IoT Hub, bypassing IoT Hub’s documented 128 KB message payload limit, and the attacker’s ability to overwrite executable memory on the target device. These conditions make real‑world exploitation harder, but not impossible — particularly in device fleets where operators accept messages from diverse, less‑trusted sources or where edge gateways perform message reassembly.
Upstream maintainers implemented a fix that adds explicit, overflow‑aware allocation checks (safe_add / safe_multiply style helpers), and the patch is visible in the azure‑c‑shared‑utility repository as commit 1129147… which adds malloc size checks across affected code paths. Security scanners and vendor advisory pages list the patched commit / fixed release as the remediation. (github.com)
What Microsoft’s short MSRC phrasing means — and what it doesn’t
The literal, machine‑readable attestation
When Microsoft’s Security Response Center writes a sentence like “Azure Linux includes this open‑source library and is therefore potentially affected by this vulnerability,” that is a product‑scoped inventory statement rather than an exclusivity claim. Practically, it means Microsoft has completed an inventory mapping for the Azure Linux product family and found the upstream component mapped to this CVE in that(packages, kernels or images). That gives Azure Linux operators a clear, authoritative signal to treat the product as in‑scope and to apply vendor guidance.What the statement does not assert
The phrasing deliberately avoids saying “only Azure Linux” or “no other Microsoft product is affected.” Microsoft has also said it will publish and expand machine‑readable CSAF/VEX attestations (a program launched in October 2025) as it inventories additional product families; if other Microsoft products are later found to include the same component, Microsoft will update the CVE/VEX mapping accordingly. In short: the absenceion for product X is not evidence that product X is safe — it may simply mean Microsoft hasn’t finished the inventory for that product.This distinction matters operationally. Azure Linux customers have an immediate, actionable remediation path. Customers running other Microsoft images, appliances or artifacts must treat the MSRC arting point for their own verification steps rather than a blanket clearance for the rest of Microsoft’s catalog.
Which Microsoft products could include azure‑c‑shared‑utility?
There is a short, practical hierarchy of products and artifacts where the azure‑c‑shared‑utility or the Azure IoT C SDK may plausibly appear:- Azure Linux distribution images and packages — confirmed by MSRC at in question; these are the direct, primary carrier Microsoft has publicly inventory‑checked.
- Azure Marketplace images and VM gallery images — many Marketplace images are assembled from distribution snapshots and can inherit user‑space libraries and packages; some Marketplace publishers also embed IoT components into endpoint images intended for devices and gateways.
- Azure IoT Edge modules, device agents or sample firmware images that Microsoft publishes or includes as part of device SDK bundles — the azure‑c‑shared‑utility is a library used by the Azure IoT C SDK and by adapter layers that feed higher‑level SDKs.
- Vendor or partner appliances sold via Microsoft channels — these sometimes include prebuilt, embedded Linux stacks or device agent binaries that could carry the vulnerable library if the builder used an affected upstream snapshot.
- Microsoft internal artifacts that ship binaries to customers — for example, if Microsoft publishes an SDK binary, container image, or appliance that statically links the affected library, that artifact would also be at risk.
- Less likely: the WSL2 kernel, Windows host components or core Windows services — the library in question is a user‑space C helper for IoT communication, not a kernel module. It is therefore less likely to appear inside Windows kernel builds; however, any cross‑platform product that bundles or ships IoT SDKs (for device management, edge tooling, or cross‑compiled agents) remains a potential carrier until inventory verification is complete.
Evidence: what independent sources say about the defect and the fix
- NVD’s published entry for CVE‑2024‑29195 documents the integer wraparound / heap overflow behavior and points at the upstream fix commit for azure‑c‑shared‑utility. That entry describes the exploitation preconditions and confirms the presence of a code change that addresses the issue.
- Distribution advisories (Ubuntu, Debian security trackers) include CVE‑2024‑29195 in their registries and assign standard severities, demonstrating that packagers considered the library a component worth tracking in distribution snapshots. This is a practical confirmation the library is shipped in multiple Linux distributions and images.
- Security vendors (Snyk, Wiz, Tenable) published technical summaries and mitigation guidance: Snyk indicates an upgrade to the patched azure‑c‑shared‑utility release (2024‑02‑08 or later) and Wiz/Tenable provide impact and scanner coverage guidance. These sources corroborate the technical fix and recommended remedial action.
- The upstream fix is visible in the GitHub repository: commit 1129147 adds explicit malloc size checks and replaces unsafe realloc patterns with overflow‑aware code, closing the integer wraparound vector. That commit is the canonical upstream remediation and the anchor point for distributor updates. (github.com)
Practical risk assessment for Microsoft customers
- Attack surface and exploitability: the vulnerability is in a user‑space IoT communication helper used mainly by device and gateway software. Realistic remote exploitation requires several adverse conditions (compromised Azure account, bypassing Azure IoT Hub message size limits, or being able to feed malformed payloads to an otherwise open endpoint). That combination lowers the probability of widespread exploitation in well‑configured environments but keeps the risk real for device fleets with lax ingress controls.
- Impact if exploited: successful exploitation can allow code execution on an IoT device, which for many deployments means a complete compromise of device integrity and confidentiality. For industrial or critical‑infrastructure deployments, this is high impact even if the exploit path is nontrivial.
- Distribution and carrier likelihood across Microsoft products: Azure Linux is a confirmed carrier. Other Microsoft images that contain the IoT C SDK or that embed device agents are plausible carriers. Core Windows product codepaths and kernel artifacts are unlikely carriers because the library is not a kernel component, but third‑party or partner images distributed by Microsoft could be at risk until inventory is confirmed. The Microsoft VEX/CSAF program expansion is the mechanism by which Microsoft will declare additional product mappings; until that inventory is complete, defenders must verify artifacts they run.
- Remediation maturity: an upstream fix exists and was merged to the azure‑c‑shared‑utility project. Linux distributors (Ubuntu, Debian) and cloud vendors have updated packages or advisories, and scanning vendors list the patch release as the remediation. This means a clear remediation path exists: update to the patched azure‑c‑shared‑utility release, rebuild dependent software, and redeploy updated ar](Add malloc size checks (#652) · Azure/azure-c-shared-utility@1129147))
Recommended actions for operators and defenders
Immediate (0–72 hours)
- Treat Microsoft’s MSRC attestation for Azure Linux as a confirmed, actionable signal: apply the updated azure‑iothub/azure‑iot‑sdk packages provided by Microsoft for Azure Linux images and follow the vendor’s published patch schedule. Azure Linux customers should prioritize remediation.
- Inventory all Microsoft‑supplied images, appliances and agent packages in your environment:
- Enumerate cloud VM images (Azure Marketplace, gallery images) and container base images that came from Microsoft channels.
- Inspect WSL2 distributions or any Microsoft‑published appliance images you run.
- Search package lists for azure‑c‑shared‑utility, azure‑iot‑sdk‑c, azure‑uamqp, azure‑uamqp‑python and related packages.
- Use automated SBOMs (Software Bill of Materials) and image scanning to detect the vulnerable package name and version.
- If you find affected artifacts, upgrade them to the patched azure‑c‑shared‑utility release (or to package versions that incorporate the upstream commit). Where upgrades require rebuilds, schedule rapid rebuilds with the fixed library and redeploy.
Short term (1–4 weeks)
- Conduct targeted runtime hardening for exposed device endpoints:
- Reduce or filter incoming message sources to IoT Hub/edge gateways.
- Enforce strict authentication and authorization for device‑to‑cloud and cloud‑to‑device channels.
- Limit message sizes and apply protocol validation layers where possible.
- For shipped devices and appliances you control, push firmware or agent updates that move to the fixed azure‑c‑shared‑utility. If you cannot push updates quickly, consider containment: network segmentation, limiting management ports and restricting remote firmware updates to trusted channels.
- Use telemetry to search for anomalous payload sizes or unusual reassembly behavior that might indicate attempted exploitation attempts involving oversormed buffers.
Long term (1–3 months)
- Request or obtain SBOMs and VEX/CSAF attestations for all Microsoft product families you depend on. Microsoft’s program to publish machine‑readable attestations began in October 2025; ask your Microsoft contacts for product‑specific VEX artifacts for any Microsoft components you run. If a product’s VEX attestations aren’t yet available, treat that product as “unverified” and perform artifact‑level inspection.
- Build automated CI gates that fail builds if they include vulnerable versions of commonly abused libraries (including azure‑c‑shared‑utility). Enforce reproducible builds and pinned dependency versions for devices and appliances.
- Educate device integrators and third‑party publishers in your supply chain about this specific CVE, the fix commit and the necessity to rebuild and republish updated images.
How to verify whether a Microsoft product is affected (technical checklist)
- Inspect package lists inside the artifact (container, VM image or appliance):
- Run dpkg/rpm queries or inspect the package manifest for azure‑c‑shared‑utility, azure‑iot‑sdk‑c, azure‑uamqp, azure‑uamqp‑python and similar names.
- Check binary symbol tables and linked libraries:
- If the library is dynamically linked, ldd / objdump will reveal it.
- If the library was statically linked into a bundled binary, use strings and symbol grep for unique identifiers (function names like safe_add_size_t, or code comments introduced ).
- Compare versions / commits:
- The upstream fix is in GitHub commit 1129147…; compare the included library version or commit hash to the fixed commit. If in doubt, ask the publisher for a signed SBOM or VEX artifact.
- Use vendor attestations:
- Check Microsoft’s VEX/CSAF data for the product in question (if published) to see if the product is listed as a carrier; but do not treat the absence of a VEX as proof of safety.
- Run static scanning and open‑source supply‑chain tools:
- Tools like Snyk, Trivy, or distro scanners will typically flag CVE‑2024‑29195 if the vulnerable package is present. Cross‑validate scanner results manually for false positives/negngths and gaps in the current vendor response
- Strength: Microsoft’s decision to publish product‑scoped attestations (CSAF/VEX) gives customers a machine‑readable, deterministic way to map CVEs to Microsoft product artifacts. Beginning with Azure Linux and expanding outward is a pragmatic rollout strategy that helps customers triage quickly. That transparency is a meaningful improvement over opaque advisories.
- Strength: Upstream remediation was quick, with an obvious, reviewable fix committed to the azure‑c‑shared‑utility repo. Distribution trackers and scanners have propagated the fix into distro advisories, giving operators a clear upgrade path. (github.com)
- Gap / Risk: Microsoft’s attestation model is product‑scoped, which is the right technical abstraction for automation, but it means customers relying only on vendor attestations may miss vulnerable artifacts from other Microsoft channels (Marketplace images, partner appliances, or older published SDK bundles). Defenders must therefore couple vendor attestations with their own artifact‑level inventory.
- Gap / Risk: The exploitation path requires chaining operational failures (compromised account, message size bypass). That can lull operators into a false sense of security. In device fleets and gateway deployments where edge reassembly or brokered message handling is used, the practical attack surface can be larger than assumed. Treat the conditional exploitability as a reason to prioritize patching, not to defer it.
Conclusions and a succinct answer to the original question
Is Azure Linux the only Microsoft product that includes this open‑source library and is therefore potentially affected by CVE‑2024‑29195?- Short, evidence‑backed answer: **No — Azure Linux is the only Microsoft product Microsoft has publicly attested (so far) to include the azure‑c‑shared‑utility implicated by CVE‑2024‑29195, but that attestation is product‑scoped and not a proof that other Microsoft products cannot include the same vulnerablt has committed to expanding its CSAF/VEX attestations (a rollout that began in October 2025) and to update CVE mappings if additional Microsoft products are found to ship the component. Until those additional attestations are published, customers must verify Microsoft artifacts they run via SBOMs, package inspection and image scanning.
- Prioritize Azure Linux image updates from Microsoft.
2.oft images and artifacts in your environment for azure‑c‑shared‑utility or the Azure IoT C SDK. - Apply the upstream fix (commit 1129147… / packaged fixed releases) and rebuild/redeploy affected artifacts. (github.com)
- Treat the MSRC attestation as authoritative for Azure Linux, but perform artifact‑level verification for all other Microsoft‑supplied images until VEX attestations expand.
Source: MSRC Security Update Guide - Microsoft Security Response Center
