Stack-based buffer overflow in rsyslog - CVE-2026-93403
Published: September 22, 2026
Vulnerability identifier: #VU151556
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-93403
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a stack-based buffer overflow in the mmpstrucdata output module when parsing crafted RFC 5424 messages. A remote attacker can send a crafted RFC 5424 message containing an oversized structured-data parameter value to cause a denial of service.
Only configurations that load and use mmpstrucdata and permit sufficiently large messages are affected.
Affected software
rsyslog
How to mitigate CVE-2026-93403
Install security update from vendor's website.
rsyslog - update to 8.2606.0