CVE-2026-61548
Rsyslog: mmpstrucdata stack buffer overflow with oversized RFC5424 structured data
- State
- Published
- Severity
- 8.1 High
- Published
- Sep 18, 2026
- Updated
- Sep 21, 2026
- Reserved
- Jul 10, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | GitHub_M |
Weaknesses
- CWE-121 Stack-based Buffer Overflow
Affected Products
| Product | Versions |
|---|---|
rsyslogrsyslog |
|
References
- https://github.com/rsyslog/rsyslog/security/advisories/GHSA-8qmr-c66f-g368
- https://github.com/rsyslog/rsyslog/pull/6991
- https://github.com/rsyslog/rsyslog/commit/bcda60a3692efdf0c8e44102528f5a0ebe0dec6d
- https://github.com/rsyslog/rsyslog/releases/tag/v8.2606.0
- http://www.openwall.com/lists/oss-security/2026/07/20/1
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