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CVE Record

CVE-2021-45932: wolfSSL wolfMQTT 1.9 has a heap-based buffer overflow (4 bytes) in MqttDecode_Publish (called from MqttClie...

wolfSSL wolfMQTT 1.9 has a heap-based buffer overflow (4 bytes) in MqttDecode_Publish (called from MqttClient_DecodePacket and MqttClient_HandlePacket).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-45932 is a memory corruption flaw in wolfSSL wolfMQTT 1.9. A malformed MQTT publish packet could trigger a small heap-based buffer overflow during packet decoding. The public bundle does not provide CVSS, impact detail, or affected CPEs, so business urgency depends on whether wolfMQTT 1.9 is used in exposed or safety-critical MQTT clients.

Executive priority

Treat this as a targeted dependency risk, not a confirmed emergency. Prioritize environments where MQTT clients process untrusted broker traffic, embedded devices are hard to patch, or wolfMQTT is part of operational technology.

Technical view

wolfMQTT 1.9 has a 4-byte heap-based buffer overflow in MqttDecode_Publish, reached via MqttClient_DecodePacket and MqttClient_HandlePacket. The supplied references include an OSS-Fuzz record, Chromium issue, and wolfMQTT commit. The bundle does not provide CVSS, CWE, exploitability detail, or a named fixed release.

Likely exposure

Exposure is likely limited to software that embeds or ships wolfSSL wolfMQTT 1.9 and parses MQTT publish packets. The source bundle lists no CPEs or downstream products, so teams must verify direct and vendored dependency use.

Exploitation context

The CVE is not listed as KEV in the supplied bundle. The available evidence points to OSS-Fuzz discovery and a source commit, not confirmed real-world exploitation. No cited source in the bundle supports active exploitation.

Researcher notes

Key gaps are severity, CWE classification, CPE coverage, exploit status, and fixed release mapping. Research should focus on confirming affected versions, commit inclusion, downstream vendors, and whether MQTT publish decoding is reachable from untrusted network paths.

Mitigation direction

  • Inventory applications, firmware, and vendors using wolfMQTT 1.9.
  • Review wolfSSL guidance and the referenced wolfMQTT fix commit.
  • Update to a wolfMQTT release that includes the fix, when vendor guidance confirms it.
  • Rebuild and redeploy affected components after dependency remediation.
  • Limit untrusted MQTT connectivity where wolfMQTT 1.9 cannot be quickly replaced.

Validation and detection

  • Check SBOMs, lockfiles, and build manifests for wolfMQTT 1.9.
  • Confirm vendored wolfMQTT code includes the referenced fix commit or later equivalent.
  • Run regression tests for MQTT publish packet decoding after updating.
  • Verify exposed MQTT-dependent products do not rely on vulnerable wolfMQTT builds.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-45932 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.