CVE-2023-41045 is a low-severity (CVSS 3.7) CWE-345 vulnerability in org.graylog2:graylog2-server. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.graylog2:graylog2-server — see the affected versions and patch details below.
Insecure source port usage for DNS queries in Graylog
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-41045.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.graylog2:graylog2-server☕org.graylog2:graylog2-serverReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.graylog2:graylog2-server | ≥ 5.1.0&&< 5.1.3 | 5.1.3org.graylog2:graylog2-server:5.1.3 |
| ☕Maven | org.graylog2:graylog2-server | all versions | 5.0.9org.graylog2:graylog2-server:5.0.9 |
Affected Products
grayloggraylogResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.graylog2:graylog2-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.graylog2:graylog2-server to 5.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-41045 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2023-41045 in your dependencies?
Find it across Maven, including transitive dependencies.