CVE-2026-61633 (CVSS 2)

Description

NanoMQ is an MQTT broker. Prior to 0.24.14, the NanoMQ client function nni_mqtt_msg_decode_unsubscribe() in nng/src/supplemental/mqtt/mqtt_codec.c does not handle a failed read_uint16() while counting topics in a malformed UNSUBSCRIBE packet. A zero-length topic followed by trailing data can leave buf.curpos unchanged while topic_count continues to increase, allowing a malicious MQTT broker to hang a connecting MQTT 3.1.1 client, consume CPU and memory, and repeatedly deny service when automatic reconnection is enabled. The broker-side nmq_unsubinfo_decode path is not affected. This issue is fixed in version 0.24.14.

Is your site exposed to CVE-2026-61633?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

2.0

LOW

CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L

EPSS — Exploit Prediction

0.0034

Probability of exploitation

0.26%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-835 CWE-835

References

Other References

https://github.com/nanomq/NanoNNG/commit/fa8d859bb39841e46cfc6cce280d242bd782ad3d https://github.com/nanomq/NanoNNG/pull/1518 https://github.com/nanomq/nanomq/releases/tag/0.24.14 https://github.com/nanomq/nanomq/security/advisories/GHSA-m7mp-rr3v-hmhr https://github.com/nanomq/nanomq/security/advisories/GHSA-m7mp-rr3v-hmhr

Frequently Asked Questions

What is CVE-2026-61633? +

NanoMQ is an MQTT broker. Prior to 0.24.14, the NanoMQ client function nni_mqtt_msg_decode_unsubscribe() in nng/src/supplemental/mqtt/mqtt_codec.c does not handle a failed read_uint16() while counting topics in a malformed UNSUBSCRIBE packet. A zero-length topic followed by trailing data can leave buf.curpos unchanged while topic_count continues to increase, allowing a malicious MQTT broker to hang a connecting MQTT 3.1.1 client, consume CPU and memory, and repeatedly deny service when automatic reconnection is enabled. The broker-side nmq_unsubinfo_decode path is not affected. This issue is fixed in version 0.24.14. It has a CVSS v3.1 base score of 2.0 (LOW).

How severe is CVE-2026-61633? +

CVE-2026-61633 has a CVSS v3.1 score of 2.0 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0034, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-61633? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-27497

OpenDJ is an LDAPv3 compliant directory service. OpenDJ prior to 4.9.3 contains a denial-of-service (DoS) vulnerability that causes the server …

CVE-2025-29776

Azle is a WebAssembly runtime for TypeScript and JavaScript on ICP. Calling `setTimer` in Azle versions `0.27.0`, `0.28.0`, and `0.29.0` …

CVE-2025-32029

ts-asn1-der is a collection of utility classes to encode ASN.1 data following DER rule. Incorrect number DER encoding can lead …

CVE-2024-8088

There is a HIGH severity vulnerability affecting the CPython "zipfile" module affecting "zipfile.Path". Note that the more common API "zipfile.ZipFile" …

CVE-2026-63570

Loop with unreachable exit condition in Pkcs12Store.GetCertificateChain in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker …

CVE-2026-113792

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, calling PdfWriter.find_outline_item on a crafted PDF with a …

CVE-2026-61633