CVE-2024-35492
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCesanta Mongoose commit b316989 was discovered to contain a NULL pointer dereference via the scpy function at src/fmt.c. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted MQTT packet.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceCesanta Mongoose networking library contains a NULL pointer dereference vulnerability in the scpy string copy function in src/fmt.c. When processing a crafted MQTT packet, the scpy function receives a NULL pointer as its source argument, causing a crash and resulting in Denial of Service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Locate the Cesanta Mongoose library installationSearch for files named mongoose.c, mongoose.h, or libmongoose in your project or system directories. Check build configuration files (Makefile, CMakeLists.txt) for references to Mongoose library source files.Affected if The library is present in your environment.
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Determine the installed version of MongooseCheck version.h, mongoose.h, or the main source files for a VERSION or MG_VERSION macro definition. Look for version tags in git repositories or release notes associated with the library files.Affected if The version is older than the patched release containing NULL pointer validation in scpy (src/fmt.c).
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Verify MQTT protocol support is enabledInspect your build configuration or source code for MG_ENABLE_MQTT define or similar MQTT compilation flags. Check if your application initializes MQTT client or server functionality using mg_mqtt_* functions.Affected if MQTT support is compiled in and actively used.
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Confirm the scpy function lacks NULL pointer protectionExamine src/fmt.c in your Mongoose library source for the scpy function implementation. Look for NULL checks or validation of the source pointer before dereferencing.Affected if The scpy function directly dereferences the source pointer without validating it is non-NULL.
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Assess exposure to external MQTT inputDetermine if your application accepts MQTT connections from untrusted sources or processes MQTT packets from external network endpoints without prior validation.Affected if Your service processes MQTT packets from network clients without sanitizing input before passing to the vulnerable code path.
You are affected if you are running a version of Cesanta Mongoose without the scpy NULL pointer fix, have MQTT support enabled, and process MQTT packets from untrusted sources that could pass a NULL pointer to the vulnerable function.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate to a patched version of Cesanta Mongoose that includes proper NULL pointer validation in the scpy function, or implement input validation to reject malformed MQTT packets before they reach the vulnerable code path.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2024-35492 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-35492 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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