CVE-2026-35217 (GCVE-0-2026-35217)

Vulnerability from cvelistv5 – Published: 2026-07-20 16:39 – Updated: 2026-07-20 17:53
VLAI
Title
NanoMQ Incorrectly Accepts a Malformed SUBSCRIBE and Can Be Driven into an ASAN-Detectable Out-of-Bounds Read
Summary
NanoMQ contains a protocol-semantics flaw in its MQTT v5 `SUBSCRIBE` handling: if a subscription entry is missing the final 1-byte `Subscription Options` field, the broker may still accept the malformed packet and install the subscription into internal broker state. Under a specific packet-length construction, the same parser flaw also causes a 1-byte out-of-bounds read that crosses the real heap allocation boundary and is detected by ASAN as a `heap-buffer-overflow`. If the consumed byte happens to look acceptable, NanoMQ may continue and append the malformed subscription entry into its internal `subinfol` state. In that case, a `SUBSCRIBE` packet that should be rejected by MQTT rules is instead treated as a successful subscription. Whether ASAN reports the bug does not depend on MQTT's logical `remain` boundary; it depends on whether the read crosses the real heap allocation boundary of the underlying message buffer. In other words, these are not two unrelated issues. They are two manifestations of the same parsing defect: by default, it appears as a semantic vulnerability, and under suitable input conditions, it also becomes a verifiable out-of-bounds read vulnerability.
Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
Impacted products
Vendor Product Version
nanomq nanomq Affected: <= 0.24.14
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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