{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-55841", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-17T16:29:38.865Z", "datePublished": "2026-08-28T22:11:08.747Z", "dateUpdated": "2026-08-28T22:11:08.747Z"}, "containers": {"cna": {"title": "Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message", "problemTypes": [{"descriptions": [{"cweId": "CWE-138", "lang": "en", "description": "CWE-138: Improper Neutralization of Special Elements", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj"}, {"name": "https://github.com/Graylog2/graylog2-server/pull/26050", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/pull/26050"}, {"name": "https://github.com/Graylog2/graylog2-server/pull/26056", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/pull/26056"}, {"name": "https://github.com/Graylog2/graylog2-server/pull/26057", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/pull/26057"}, {"name": "https://github.com/Graylog2/graylog2-server/pull/26059", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/pull/26059"}, {"name": "https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f"}, {"name": "https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627"}, {"name": "https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d"}, {"name": "https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d", "tags": ["x_refsource_MISC"], "url": "https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d"}], "affected": [{"vendor": "Graylog2", "product": "graylog2-server", "versions": [{"version": "< 6.3.12", "status": "affected"}, {"version": ">= 7.0.0-alpha.1, < 7.0.7", "status": "affected"}, {"version": ">= 7.1.0-alpha.1, < 7.1.2", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-28T22:11:08.747Z"}, "descriptions": [{"lang": "en", "value": "Graylog is a free and open log management platform. Prior to Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3, the FortiGate key-value syslog parser in graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java and graylog2-server/src/main/java/org/graylog2/inputs/codecs/SyslogCodec.java mishandles field-like text inside quoted values. GLFortiGateSyslogEvent.getFields() uses KV_PATTERN and QUOTED_KV_PATTERN, while SyslogCodec.parse() invokes the FortiGateSyslogEvent parser; crafted values containing = or backslash-escaped quotes can cause embedded keys such as srcip, dstip, date, time, and tz to remove or overwrite original top-level fields or produce an invalid message that Graylog discards. An unauthenticated network sender who can submit syslog messages can therefore manipulate security-log fields or evade logging to obscure malicious activity. This issue is fixed in Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3."}], "source": {"advisory": "GHSA-gqr6-r77p-c2pj", "discovery": "UNKNOWN"}}}}

{}

{"affected": [{"affectedData": [{"product": "graylog2-server", "vendor": "Graylog2", "versions": [{"status": "affected", "version": "< 6.3.12"}, {"status": "affected", "version": ">= 7.0.0-alpha.1, < 7.0.7"}, {"status": "affected", "version": ">= 7.1.0-alpha.1, < 7.1.2"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Graylog is a free and open log management platform. Prior to Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3, the FortiGate key-value syslog parser in graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java and graylog2-server/src/main/java/org/graylog2/inputs/codecs/SyslogCodec.java mishandles field-like text inside quoted values. GLFortiGateSyslogEvent.getFields() uses KV_PATTERN and QUOTED_KV_PATTERN, while SyslogCodec.parse() invokes the FortiGateSyslogEvent parser; crafted values containing = or backslash-escaped quotes can cause embedded keys such as srcip, dstip, date, time, and tz to remove or overwrite original top-level fields or produce an invalid message that Graylog discards. An unauthenticated network sender who can submit syslog messages can therefore manipulate security-log fields or evade logging to obscure malicious activity. This issue is fixed in Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3."}], "id": "CVE-2026-55841", "lastModified": "2026-08-28T23:17:07.840", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-28T23:17:07.840", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/pull/26050"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/pull/26056"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/pull/26057"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/pull/26059"}, {"source": "security-advisories@github.com", "url": "https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-138"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.3.12)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.0.0-alpha.1,7.0.7)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.1.0-alpha.1,7.1.2)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "graylog2-server", "source": "cna", "vendor": "Graylog2"}, "product": "graylog2-server", "vendor": "graylog2"}], "created": "2026-08-28T23:45:02.997263+00:00", "updated": "2026-08-28T23:45:03.127299+00:00", "vendors": ["graylog2", "graylog2$PRODUCT$graylog2-server"]}