CVE-2026-61548

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{"affected": [{"affectedData": [{"product": "rsyslog", "vendor": "rsyslog", "versions": [{"status": "affected", "version": ">= 7.5.4, < 8.2606.0"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-61548", "lastModified": "2026-09-24T21:22:19.873", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 5.9, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-61548", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-09-18T19:24:39.206415Z", "version": "2.0.3"}}]}, "published": "2026-09-18T17:16:58.190", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/rsyslog/rsyslog/commit/bcda60a3692efdf0c8e44102528f5a0ebe0dec6d"}, {"source": "security-advisories@github.com", "url": "https://github.com/rsyslog/rsyslog/pull/6991"}, {"source": "security-advisories@github.com", "url": "https://github.com/rsyslog/rsyslog/releases/tag/v8.2606.0"}, {"source": "security-advisories@github.com", "url": "https://github.com/rsyslog/rsyslog/security/advisories/GHSA-8qmr-c66f-g368"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "http://www.openwall.com/lists/oss-security/2026/07/20/1"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-121"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"bugzilla": {"description": "rsyslog: Rsyslog: Denial of Service due to stack buffer overflow in mmpstrucdata plugin", "id": "2538148", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2538148"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-120", "details": ["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.", "A flaw was found in Rsyslog, a system for log processing. A remote unauthenticated attacker could exploit a stack buffer overflow vulnerability within the optional `mmpstrucdata` plugin. By sending a specially crafted RFC5424 message containing an oversized structured-data parameter, the attacker can cause a system crash, leading to a denial of service (DoS) and interruption of log collection. This issue affects deployments that have the `mmpstrucdata` plugin installed and configured to accept messages exceeding the buffer size."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, ensure the `mmpstrucdata` plugin is not loaded or used in rsyslog configurations where it is not essential. If the plugin is required, restrict network access to the rsyslog service to trusted sources. Additionally, review and adjust the `MaxMessageSize` configuration to prevent the processing of excessively large structured-data parameters.\n*Warning: Changes to rsyslog configuration may require a service restart, which will temporarily interrupt log collection.*"}, "name": "CVE-2026-61548", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "rsyslog", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "rsyslog", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "rsyslog7", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "rsyslog", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "rsyslog", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "rhel9/rsyslog", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "rsyslog", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-09-18T16:54:28Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-61548\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-61548\nhttp://www.openwall.com/lists/oss-security/2026/07/20/1\nhttps://github.com/rsyslog/rsyslog/commit/bcda60a3692efdf0c8e44102528f5a0ebe0dec6d\nhttps://github.com/rsyslog/rsyslog/pull/6991\nhttps://github.com/rsyslog/rsyslog/releases/tag/v8.2606.0\nhttps://github.com/rsyslog/rsyslog/security/advisories/GHSA-8qmr-c66f-g368"], "threat_severity": "Important"}

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