Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message
Summary
| CVE | CVE-2026-55841 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-28 23:17:07 UTC |
| Updated | 2026-08-28 23:17:07 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Problem Types: CWE-138 | CWE-138 CWE-138: Improper Neutralization of Special Elements
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
| 3.1 | CNA | DECLARED | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Graylog2 | Graylog2-server | affected < 6.3.12 | Not specified |
| CNA | Graylog2 | Graylog2-server | affected >= 7.0.0-alpha.1, < 7.0.7 | Not specified |
| CNA | Graylog2 | Graylog2-server | affected >= 7.1.0-alpha.1, < 7.1.2 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/Graylog2/graylog2-server/pull/26059 | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/pull/26056 | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0f... | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077... | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8... | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083... | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/pull/26050 | [email protected] | github.com | |
| github.com/Graylog2/graylog2-server/pull/26057 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.