Out-of-bounds Read in Emqx Nanomq
CVE-2026-34608
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (44.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 44.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.002
Affected products
- Emqx Nanomq
- Nanomq — versions < 0.24.10
Weakness classification (CWE)
References
- github.com/nanomq/nanomq/security/advisories/GHSA-8p57-jxj9-3qq3 (Exploit, Mitigation, Vendor Advisory)
- github.com/nanomq/nanomq/commit/9499a4b2c47998a6aadb69238c18b9e6771b1691 (Patch)
- github.com/nanomq/nanomq/releases/tag/0.24.10 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-34608?
- CVE-2026-34608 is a medium-severity vulnerability in Emqx Nanomq, classified under Out-of-bounds Read. CVSS score: 4.9/10. Published 2026-04-02.
- How severe is CVE-2026-34608?
- Medium severity. CVSS v3 base score is 4.9 out of 10.