CVE-2026-34608nanomq: Heap-Buffer-Overflow in webhook_inproc.c via cJSON_Parse OOB Read

Official description

NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. Prior to version 0.24.10, in NanoMQ's webhook_inproc.c, the hook_work_cb() function processes nng messages by parsing the message body with cJSON_Parse(body). The body is obtained from nng_msg_body(msg), which is a binary buffer without a guaranteed null terminator. This leads to an out-of-bounds read (OOB read) as cJSON_Parse reads until it finds a \0, potentially accessing memory beyond the allocated buffer (e.g., nng_msg metadata or adjacent heap/stack). The issue is often masked by nng's allocation padding (extra 32 bytes of zeros for non-power-of-two sizes <1024 or non-aligned). The overflow is reliably triggered when the JSON payload length is a power-of-two >=1024 (no padding added). This issue has been patched in version 0.24.10.

Affected products (as reported)

References

• https://github.com/nanomq/nanomq/security/advisories/GHSA-8p57-jxj9-3qq3 x_refsource_CONFIRM
• https://github.com/nanomq/nanomq/commit/9499a4b2c47998a6aadb69238c18b9e6771b1691 x_refsource_MISC
• https://github.com/nanomq/nanomq/releases/tag/0.24.10 x_refsource_MISC