Stack-based buffer overflow in rsyslog - CVE-2026-61548
Published: July 20, 2026
Vulnerability identifier: #VU138583
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-61548
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: rsyslog.com
Affected software:
rsyslog
rsyslog
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to stack-based buffer overflow in the mmpstrucdata plugin parseSD_PARAM()/parsePARAM_VALUE() handling when parsing oversized RFC5424 structured-data parameter values. A remote attacker can send a specially crafted RFC5424 message to cause a denial of service.
Only deployments where the optional plugin is installed, explicitly loaded and used, attacker-controlled RFC5424 structured data reaches that action, and MaxMessageSize is high enough to permit an oversized parameter value are vulnerable.
How to mitigate CVE-2026-61548
Install security update from vendor's website.