CVE-2026-61548 Rsyslog: mmpstrucdata stack buffer overflow with oversized RFC5424 structured data
Remote attackers can cause a denial of service in Rsyslog by sending oversized RFC5424 messages to the optional mmpstrucdata plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-61548?
CVE-2026-61548 is a high-severity memory corruption vulnerability in rsyslog, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-121
Which versions are affected by CVE-2026-61548?
Linux distribution packages (21)
rsyslog SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 8.2406.0-150700.3.7.1 |
rsyslog SUSE:Linux Enterprise Module for Package Hub 15 SP7 | All versions | 8.2406.0-150700.3.7.1 |
rsyslog SUSE:Linux Enterprise Module for Server Applications 15 SP7 | All versions | 8.2406.0-150700.3.7.1 |
rsyslog SUSE:Linux Enterprise Server 12 SP5-LTSS | All versions | 8.2106.0-8.22.1 |
rsyslog SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise Server 15 SP6-LTSS | All versions | 8.2406.0-150600.12.16.1 |
rsyslog SUSE:Linux Enterprise Server 16.0 | All versions | 8.2502.0-160000.4.1 |
rsyslog SUSE:Linux Enterprise Server 16.0 | All versions | 8.2502.0-160000.4.1 |
rsyslog SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 8.2106.0-8.22.1 |
rsyslog SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 8.2306.0-150400.5.40.1 |
rsyslog SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | All versions | 8.2406.0-150600.12.16.1 |
rsyslog SUSE:Linux Enterprise Server for SAP applications 16.0 | All versions | 8.2502.0-160000.4.1 |
rsyslog SUSE:Linux Enterprise Server for SAP applications 16.0 | All versions | 8.2502.0-160000.4.1 |
rsyslog openSUSE:Leap 16.0 | All versions | 8.2502.0-160000.4.1 |
rsyslog openSUSE:Tumbleweed | All versions | 8.2606.0-1.1 |
How do I fix CVE-2026-61548?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-61548 being exploited?
There is no known exploitation of CVE-2026-61548 in the wild and no public exploit code.
Sources
Also known as AZL-103314, DEBIAN-CVE-2026-61548, GHSA-8qmr-c66f-g368, SUSE-SU-2026:23122-1, SUSE-SU-2026:23145-1, SUSE-SU-2026:3442-1 and 7 more.