CVE-2026-61548

A flaw was found in Rsyslog, a system for log processing. A remote unauthenticated attacker could exploit a stack buffer overflow vulnerability within the optional mmpstrucdata plugin. By sending a specially crafted RFC5424 message containing an oversized structured-data parameter, the attacker can cause a system crash, leading to a denial of service (DoS) and interruption of log collection. This issue affects deployments that have the mmpstrucdata plugin installed and configured to accept messages exceeding the buffer size.

This vulnerability is rated as Important severity because an unauthenticated network attacker can crash the rsyslog daemon, disrupting central logging infrastructure across an environment. Standard Red Hat Enterprise Linux installations do not load or use the optional mmpstrucdata module by default, nor do default message buffer limits allow structured parameters exceeding the internal threshold. Only custom configurations that explicitly load this plugin and permit oversized network syslog messages are exposed to this issue.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.