CVE-2026-55841

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.

• github.comhttps://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f
• github.comhttps://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627
• github.comhttps://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d
• github.comhttps://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d
• github.comhttps://github.com/Graylog2/graylog2-server/pull/26050
• github.comhttps://github.com/Graylog2/graylog2-server/pull/26056
• github.comhttps://github.com/Graylog2/graylog2-server/pull/26057
• github.comhttps://github.com/Graylog2/graylog2-server/pull/26059
• github.comhttps://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj