Fortigate syslog message parser can be exploited to modify or delete fields from the original message
Impact
A security issue has been identified in Graylog affecting the parsing of syslog messages that use a key-value format, such as those generated by Fortigate devices.
The vulnerability allows attackers to overwrite individual message fields, or to produce invalid messages which Graylog will discard. This effectively enables log evasion techniques to obscure malicious activity.
Patches
The issue has been fixed in the following Graylog versions: 6.3.12, 7.0.7, 7.1.2. Users should upgrade to one of these versions or above to remediate the vulnerability.
Graylog Cloud has already been patched.
Workarounds
There are no feasible workarounds for this issue. Upgrading to a patched version is recommended.
To find potentially discarded messages due to parsing errors, customers of Graylog Enterprise or Security can check the Indexing and Processing Failures Index^1.
Credits
Thanks to Jose Luis González, from Fundación Sarenet, with additional analysis by Borja Marcos from Sarenet.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.graylog2:graylog2-server | < 6.3.12, >= 7.0.0, < 7.0.7, >= 7.1.0, < 7.1.2 | 6.3.12, 7.0.7, 7.1.2 |
References
- https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj
- https://github.com/Graylog2/graylog2-server/pull/26050
- https://github.com/Graylog2/graylog2-server/pull/26056
- https://github.com/Graylog2/graylog2-server/pull/26057
- https://github.com/Graylog2/graylog2-server/pull/26059
- 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
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- Weakness (CWE)
CWE-138- Platform
- Java / Kotlin (Maven)
- Package
org.graylog2:graylog2-server- Disclosed
- 28.08.2026
- Updated
- 11.10.2026 13:19
Sources and licenses
OSV / GitHub Advisory Database - GHSA-gqr6-r77p-c2pj - CC BY 4.0
Vulnerability history: org.graylog2:graylog2-server
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 16
- First → latest
- 05.2022 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 5
- Medium 8
- Low 3
Disclosures per year
- 2022: 3
- 2023: 3
- 2024: 2
- 2025: 4
- 2026: 4
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Fortigate syslog message parser can be exploited to modify or delete fields from the original message this entry
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