{"cve":"CVE-2026-55841","nvd":{"published":"2026-08-28T23:17:07.840","modified":"2026-09-09T21:09:13.080","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","score":7.5},"cwes":["CWE-138"],"references":["https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f","https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627","https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d","https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d","https://github.com/Graylog2/graylog2-server/pull/26050"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-55841","score":0.00633,"percentile":0.50364,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-gqr6-r77p-c2pj","url":"https://osv.dev/vulnerability/GHSA-gqr6-r77p-c2pj","summary":"Fortigate syslog message parser can be exploited to modify or delete fields from the original message","modified":"2026-08-28T22:25:38.021373Z","packages":[{"ecosystem":"Maven","name":"org.graylog2:graylog2-server","purl":"pkg:maven/org.graylog2/graylog2-server","ranges":["<6.3.12"],"fixed":["6.3.12"]},{"ecosystem":"Maven","name":"org.graylog2:graylog2-server","purl":"pkg:maven/org.graylog2/graylog2-server","ranges":[">=7.0.0 <7.0.7"],"fixed":["7.0.7"]},{"ecosystem":"Maven","name":"org.graylog2:graylog2-server","purl":"pkg:maven/org.graylog2/graylog2-server","ranges":[">=7.1.0 <7.1.2"],"fixed":["7.1.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}