{"api_version":"1","generated_at":"2026-08-29T03:55:08+00:00","cve":"CVE-2026-55841","urls":{"html":"https://cve.report/CVE-2026-55841","api":"https://cve.report/api/cve/CVE-2026-55841.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-55841","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-55841"},"summary":{"title":"Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message","description":"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.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-08-28 23:17:07","updated_at":"2026-08-28 23:17:07"},"problem_types":["CWE-138","CWE-138 CWE-138: Improper Neutralization of Special 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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."}],"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"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-138","description":"CWE-138: Improper Neutralization of Special Elements","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-28T22:11:08.747Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"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"}],"source":{"advisory":"GHSA-gqr6-r77p-c2pj","discovery":"UNKNOWN"},"title":"Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-55841","datePublished":"2026-08-28T22:11:08.747Z","dateReserved":"2026-06-17T16:29:38.865Z","dateUpdated":"2026-08-28T22:11:08.747Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-28 23:17:07","lastModifiedDate":"2026-08-28 23:17:07","problem_types":["CWE-138","CWE-138 CWE-138: Improper Neutralization of Special Elements"],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":3.6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"55841","Ordinal":"1","Title":"Graylog: Fortigate syslog message parser can be exploited to mod","CVE":"CVE-2026-55841","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"55841","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"Graylog: Fortigate syslog message parser can be exploited to mod"}]}}}