Graylog vulnerable to insecure source port usage for DNS queries
Summary
Graylog utilises only one single source port for DNS queries.
Details
Graylog seems to bind a single socket for outgoing DNS queries. That socket is bound to a random port number which is not changed again. This goes against recommended practice since 2008, when Dan Kaminsky discovered how easy is to carry out DNS cache poisoning attacks. In order to prevent cache poisoning with spoofed DNS responses, it is necessary to maximise the uncertainty in the choice of a source port for a DNS query.
PoC
The attached figure shows the source ports distribution difference between Graylog configured to use a data adapter based on DNS queries and ISC Bind. The source port distribution of the DNS queries sent from Graylog to a recursive DNS name server running Bind (CLIENT_QUERY) are depicted in purple, while the queries sent from the recursive DNS server to the authoritatives (RESOLVER_QUERY) are plotted in green color. As it can be observed, in contrast to ISC Bind which presents a heterogeneous usage of source port, Graylog utilises a single source port.
Impact
Although unlikely in many setups, an external attacker could inject forged DNS responses into a Graylog's lookup table cache. In order to prevent this, it is at least recommendable to distribute the DNS queries through a pool of distinct sockets, each of them with a random source port and renew them periodically.
(Credit to Iratxe Niño from Fundación Sarenet and Borja Marcos from Sarenet)
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.graylog2:graylog2-server | >= 5.1.0, < 5.1.3, < 5.0.9 | 5.1.3, 5.0.9 |
References
- https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-g96c-x7rh-99r3
- https://nvd.nist.gov/vuln/detail/CVE-2023-41045
- https://github.com/Graylog2/graylog2-server/commit/466af814523cffae9fbc7e77bab7472988f03c3e
- https://github.com/Graylog2/graylog2-server/commit/a101f4f12180fd3dfa7d3345188a099877a3c327
- https://github.com/Graylog2/graylog2-server
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N- Weakness (CWE)
CWE-345- Platform
- Java / Kotlin (Maven)
- Package
org.graylog2:graylog2-server- Disclosed
- 06.07.2023
- Updated
- 11.10.2026 11:21
Sources and licenses
OSV / GitHub Advisory Database - GHSA-g96c-x7rh-99r3 - 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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Graylog vulnerable to insecure source port usage for DNS queries this entry
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