Mosquitto 1.6.6 and 1.5.9 have been released to address two security vulnerabilities.
Titles and links will be updated once the CVE numbers are assigned.
CVE-xxxx-xxxxx
A vulnerability exists in Mosquitto versions 1.5 to 1.6.5 inclusive.
If a client sends a SUBSCRIBE packet containing a topic that consists of approximately 65400 or more '/' characters, i.e. the topic hierarchy separator, then a stack overflow will occur.
The issue is fixed in Mosquitto 1.6.6 and 1.5.9. Patches for older versions are available at https://mosquitto.org/files/cve/2019-hier
The fix addresses the problem by restricting the allowed number of topic hierarchy levels to 200. An alternative fix is to increase the size of the stack by a small amount.
CVE-2019-11778
A vulnerability exists in Mosquitto version 1.6 to 1.6.4 inclusive, known as CVE-2019-11778
If an MQTT v5 client connects to Mosquitto, sets a last will and testament, sets a will delay interval, sets a session expiry interval, and the will delay interval is set longer than the session expiry interval, then a use after free error occurs, which has the potential to cause a crash in some situations.
The issue is fixed in Mosquitto 1.6.5. Patches for older versions are available at https://mosquitto.org/files/cve/2019-will-delay
Version 1.6.6 Changes
The complete list of fixes addressed in version 1.6.6 is:
Security
- Restrict topic hierarchy to 200 levels to prevent possible stack overflow. Closes #1412.