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Fencer Intel
high 8.1

CVE-2026-61548 json

Rsyslog: mmpstrucdata stack buffer overflow with oversized RFC5424 structured data

published 3mo ago modified last mo. also EUVD-2026-83185 , GHSA-8qmr-c66f-g368

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository rsyslog/rsyslog. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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.

Patch / fix

  • rsyslog rsyslog 8.2606.0
  • rsyslog Debian 12 8.2302.0-1+deb12u2
  • rsyslog Debian 13 8.2504.0-1+deb13u2
  • rsyslog Debian 14 8.2606.0-4

debian advisories DEBIAN-CVE-2026-61548

  • rsyslog Ubuntu 22.04 LTS 8.2112.0-2ubuntu2.4
  • rsyslog Ubuntu 24.04 LTS 8.2312.0-3ubuntu9.3
  • rsyslog Ubuntu 26.04 LTS 8.2512.0-1ubuntu4.1

ubuntu advisories UBUNTU-CVE-2026-61548

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rsyslog SLES 16.0, SLES for SAP applications 16.0 8.2608.0-160000.1.1
  • rsyslog SLE Module for Server Applications 15 SP7, SLE Module for Package Hub 15 SP7, SLE Module for Basesystem 15 SP7 8.2608.0-150700.3.24.1
  • rsyslog SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 8.2306.0-150400.5.40.1
  • rsyslog SLES 16.0, SLES for SAP applications 16.0 8.2502.0-160000.4.1
  • rsyslog SLE Module for Server Applications 15 SP7, SLE Module for Package Hub 15 SP7, SLE Module for Basesystem 15 SP7 8.2406.0-150700.3.7.1
  • rsyslog SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 8.2106.0-8.22.1
  • rsyslog SLES for SAP 15 SP6, SLES 15 SP6-LTSS 8.2406.0-150600.12.16.1

suse advisories SUSE-SU-2026:24598-1SUSE-SU-2026:4611-1SUSE-SU-2026:3518-1SUSE-SU-2026:23122-1SUSE-SU-2026:23145-1SUSE-SU-2026:3498-1

  • rsyslog openSUSE Leap 16.0 8.2608.0-160000.1.1
  • rsyslog openSUSE Leap 16.0 8.2502.0-160000.4.1
  • rsyslog openSUSE Tumbleweed 8.2606.0-1.1

opensuse advisories openSUSE-SU-2026:22184-1openSUSE-SU-2026:21535-1openSUSE-SU-2026:11407-1

  • rsyslog Alpine 3.24 8.2608.0-r0

alpine advisories ALPINE-CVE-2026-61548

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-61548 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-61548 updated cvss 7.5

rsyslog: Rsyslog: Denial of Service due to stack buffer overflow in mmpstrucdata plugin

  • Red Hat Enterprise Linux 6 rsyslog, rsyslog7, rsyslog-relp, rsyslog-snmp, rsyslog-mysql, rsyslog-pgsql, +9 more Red Hat Enterprise Linux 7 rsyslog, rsyslog-relp, rsyslog-snmp, rsyslog-kafka, rsyslog-mysql, rsyslog-pgsql, +11 more Red Hat Enterprise Linux 8 rsyslog, rsyslog-relp, rsyslog-snmp, rsyslog-kafka, rsyslog-mysql, rsyslog-pgsql, +13 more Red Hat Enterprise Linux 9 rsyslog, rsyslog-relp, rsyslog-snmp, rsyslog-kafka, rsyslog-mysql, rsyslog-pgsql, +14 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 10 rsyslog
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
last mo.

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • rsyslog rsyslog

Classification

Weakness
  • CWE-121 Stack-based Buffer Overflow

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of rsyslog/rsyslog published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.