CVE-2026-55841Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message
- 7.5HighCVSS base score
- 0.63%Exploitation in 30 daysEPSS · top 49% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 2 months later
· 2 months later
Published
- 4 days later
· 4 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
| NVDNVD · Deferred | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.63% · top 49% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- affected < 6.3.12
- affected >= 7.0.0-alpha.1, < 7.0.7
- affected >= 7.1.0-alpha.1, < 7.1.2
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavenorg.graylog2:graylog2-serverGHSA-gqr6-r77p-c2pj (opens in a new tab)
References
References9
- https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj (opens in a new tab)x_refsource_CONFIRM
- https://github.com/Graylog2/graylog2-server/pull/26050 (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/pull/26056 (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/pull/26057 (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/pull/26059 (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627 (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d (opens in a new tab)x_refsource_MISC
- https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-68013 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-gqr6-r77p-c2pj (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-55841)Record last updated .