SB2026020937 - Multiple vulnerabilities in NanoMQ
Published: February 9, 2026 Updated: April 24, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) NULL pointer dereference (CVE-ID: CVE-2025-68699)
CWE-ID: CWE-476 - NULL Pointer Dereference
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a NULL pointer dereference error when handling shared subscriptions. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.
2) NULL pointer dereference (CVE-ID: CVE-2026-32696)
CWE-ID: CWE-476 - NULL Pointer Dereference
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a null pointer dereference in auth_http.c:set_data() when processing an MQTT CONNECT request without username/password while HTTP authentication parameters use the %u and %P placeholders. A remote attacker can send a specially crafted MQTT CONNECT request to cause a denial of service.
User interaction is required.
3) Use-after-free (CVE-ID: CVE-2026-22040)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to use-after-free in the Broker process when handling a combined pattern of MQTT publish, reconnect, kick-out, and subscribe or unsubscribe operations using the same ClientID. A remote attacker can send valid MQTT control packets in a specially crafted traffic pattern to cause a denial of service.
User interaction is required, and the issue is generally reproducible under sustained high-frequency traffic conditions.
4) Out-of-bounds read (CVE-ID: CVE-2026-21888)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an out-of-bounds read in get_var_integer() when parsing MQTT v5 variable byte integers in a crafted CONNECT packet. A remote attacker can send a specially crafted network packet to cause a denial of service.
The issue is reliably reproducible in builds with AddressSanitizer enabled.
Remediation
Install update from vendor's website.