Security readout for executives and security teams
Plain-English summary
CVE-2021-45936 is a heap-based buffer overflow reported in wolfSSL wolfMQTT 1.9 when decoding MQTT DISCONNECT handling. For businesses, urgency depends on whether wolfMQTT 1.9 is present in products or services that process untrusted MQTT traffic.
Executive priority
Treat as a targeted dependency remediation item. Prioritize products using wolfMQTT 1.9 on exposed MQTT paths, especially embedded or operational environments where updates take longer.
Technical view
The reported flaw is in MqttDecode_Disconnect, reached through MqttClient_DecodePacket and MqttClient_WaitType. Sources identify heap memory corruption, but do not provide CVSS, precise impact, exploitability, or a named fixed release in the supplied bundle.
Likely exposure
Exposure is likely limited to applications, embedded products, or services that include wolfSSL wolfMQTT 1.9 and parse MQTT packets from external or untrusted peers.
Exploitation context
The CVE is not listed as KEV in the supplied bundle, and no cited source states active exploitation. OSS-Fuzz references suggest the issue was found through fuzz testing.
Researcher notes
Evidence is sparse: the bundle gives function names, vulnerability class, wolfMQTT 1.9, OSS-Fuzz linkage, and an upstream commit reference. It does not substantiate active exploitation, CVSS severity, affected CPEs, or a fixed release number.
Mitigation direction
- Inventory codebases and firmware for wolfMQTT 1.9 usage.
- Review wolfSSL wolfMQTT vendor guidance and the referenced upstream commit.
- Upgrade or patch wolfMQTT where vendor-supported fixes are available.
- Reduce exposure of MQTT clients to untrusted network peers where feasible.
- Monitor vendor advisories for fixed-release confirmation.
Validation and detection
- Confirm whether wolfMQTT is present in application or firmware dependencies.
- Identify the exact wolfMQTT version built into deployed artifacts.
- Check whether the referenced upstream commit is included in your build.
- Review MQTT-facing components for untrusted DISCONNECT packet handling paths.
- Run regression tests around MQTT connection teardown behavior.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-45936 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/wolfSSL/wolfMQTT/commit/84d4b53122e0fa0280c7872350b89d5777dabbb2CVE reference · x_refsource_MISC
- https://github.com/google/oss-fuzz-vulns/blob/main/vulns/wolfmqtt/OSV-2021-1348.yamlCVE reference · x_refsource_MISC
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=39053CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.