CVE-2024-30166
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 · uneditedIn Mbed TLS 3.3.0 through 3.5.2 before 3.6.0, a malicious client can cause information disclosure or a denial of service because of a stack buffer over-read (of less than 256 bytes) in a TLS 1.3 server via a TLS 3.1 ClientHello.
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 · high confidenceA stack buffer over-read vulnerability exists in Mbed TLS versions 3.3.0 through 3.5.2 where a malicious TLS 1.3 server client can send a TLS 3.1 ClientHello message, causing the server to read up to 256 bytes beyond the intended buffer boundary on the stack, leading to potential information disclosure or denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 3.3.0, < 3.6.0CVSS 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
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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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Identify Mbed TLS library versionCheck the version of the installed Mbed TLS library. Common methods: (1) Check mbedtls/version.h for MBEDTLS_VERSION_NUMBER macro, (2) Run 'grep -r "MBEDTLS_VERSION"' on include files, (3) Check packaging metadata if installed via package manager, (4) Query the library at runtime via mbedtls_version_get_number(). Compare the version number against the affected range: 3.3.0 <= version < 3.6.0.Affected if The installed Mbed TLS version is 3.3.0 through 3.5.2 (or any version < 3.6.0).
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Verify TLS 1.3 support is enabledInspect the Mbed TLS configuration header (commonly mbedtls_config.h or the built configuration). Look for the preprocessor macro MBEDTLS_SSL_PROTO_TLS1_3 or check if TLS 1.3 cipher suites are defined. This can be done by searching the config file for 'TLS 1.3' or 'MBEDTLS_SSL_PROTO_TLS1_3' defined to 1.Affected if TLS 1.3 protocol support is compiled/enabled in the Mbed TLS build.
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Determine if the application acts as a TLS 1.3 serverReview the application code or deployment configuration to determine if the system initializes an SSL context as a server (mbedtls_ssl_config_defaults called with MBEDTLS_SSL_IS_SERVER or listening on a port for TLS connections). Check if the application calls mbedtls_ssl_accept or uses the server-side SSL workflow.Affected if The system runs as a TLS 1.3 server (accepts incoming TLS connections).
You are affected if you run any Mbed TLS version between 3.3.0 and 3.5.2 (exclusive of 3.6.0), have TLS 1.3 support enabled, and your application functions as a TLS 1.3 server that can receive ClientHello messages from clients.
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.
dbcve · scoped3.6.0
Upgrade Mbed TLS library to version 3.6.0 or later to patch the vulnerability. If immediate upgrade is not feasible, consider filtering or rejecting TLS 3.1 ClientHello messages at the network boundary.
Mbed TLS 3.6.0
- 1. Identify all systems running Mbed TLS versions 3.3.0 through 3.5.2.
- 2. Review the Mbed TLS 3.6.0 release notes for any compatibility concerns with your implementation.
- 3. Update Mbed TLS to version 3.6.0 or later in all affected environments.
- 4. Verify the update was successful by checking the library version.
- 5. Test TLS 1.3 server functionality to ensure normal operation after the update.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-30166 — 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-2024-30166 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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