CVE-2026-61548 — Rsyslog: mmpstrucdata stack buffer overflow with oversized RFC5424 structured data

Affected: rsyslog

Rsyslog is a rocket-fast system for log processing. From 7.5.4 until 8.2606.0, the optional mmpstrucdata plugin's parseSD_PARAM function in plugins/mmpstrucdata/mmpstrucdata.c stores RFC5424 parameter values in a fixed pVal[32 * 1024] stack buffer and calls parsePARAM_VALUE without supplying the destination size. A remote unauthenticated attacker whose crafted RFC5424 message reaches an action using mmpstrucdata can provide a structured-data parameter larger than that buffer when MaxMessageSize permits it, causing an attacker-controlled stack overwrite. Deployments that do not install and use the plugin, or whose effective message-size limit remains below the required threshold, are not affected by this issue. The demonstrated impact is a crash and interruption of log collection; code execution is not demonstrated. This issue is fixed in version 8.2606.0.

USN-8598-1 — rsyslog vulnerabilities

Affected: Ubuntu:22.04:LTS: rsyslog, Ubuntu:24.04:LTS: rsyslog, Ubuntu:26.04:LTS: rsyslog

It was discovered that rsyslog incorrectly handled regex-based TCP framing in the imptcp module. A remote attacker could possibly use this issue to cause rsyslog to crash, resulting in a denial of service.

It was discovered that rsyslog incorrectly handled oversized RFC5424 structured data in the mmpstrucdata module. A remote attacker could possibly use this issue to cause rsyslog to crash, resulting in a denial of service. (CVE-2026-61548)

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CVE-2026-61548 — Rsyslog: mmpstrucdata stack buffer overflow with oversized RFC5424 structured data

USN-8598-1 — rsyslog vulnerabilities