Graylog up to 6.3.11/7.0.6/7.1.1 FortiGate key-value syslog parser GLFortiGateSyslogEvent.java GLFortiGateSyslogEvent.getFields escape output

Summaryinfo

A vulnerability marked as problematic has been reported in Graylog up to 6.3.11/7.0.6/7.1.1. This affects the function GLFortiGateSyslogEvent.getFields of the file graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java of the component FortiGate key-value syslog parser. Performing a manipulation results in escape output. This vulnerability is identified as CVE-2026-55841. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in Graylog up to 6.3.11/7.0.6/7.1.1. This affects the function GLFortiGateSyslogEvent.getFields of the file graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java of the component FortiGate key-value syslog parser. The manipulation with an unknown input leads to a escape output vulnerability. CWE is classifying the issue as CWE-116. The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved. This is going to have an impact on integrity. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-55841 since 06/17/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Upgrading to version 6.3.12, 7.0.7 or 7.1.2 eliminates this vulnerability.

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Productinfo

Name

• Graylog

Version

• 6.3.0
• 6.3.1
• 6.3.2
• 6.3.3
• 6.3.4
• 6.3.5
• 6.3.6
• 6.3.7
• 6.3.8
• 6.3.9
• 6.3.10
• 6.3.11
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.1.0
• 7.1.1

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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