CVE-2025-68699mediumCWE-476

CVE-2025-68699: medium-severity vulnerability in nanomq

NanoMQ $share/ Subscription Validation and Forwarding Parsing Inconsistency: NULL Pointer Increment Causes Crash

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.5epss 0.3%
NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. In version 0.24.6, NanoMQ has a protocol parsing / forwarding inconsistency when handling shared subscriptions ($share/). A malformed SUBSCRIBE topic such as $share/ab (missing the second /) is not strictly validated during the subscription stage, so the invalid Topic Filter is stored into the subscription table. Later, when any PUBLISH matches this subscription, the broker send path (nmq_pipe_send_start_v4/v5) performs a second $share/ parsing using strchr() and increments the returned pointer without NULL checks. If the second strchr() returns NULL, sub_topic++ turns the pointer into an invalid address (e.g. 0x1). This invalid pointer is then passed into topic_filtern(), which triggers strlen() and crashes with SIGSEGV. The crash is stable and remotely triggerable. This issue has been patched in version 0.24.7.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Affected products
nanomq · nanomq
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