GHSA-cfxw-4h78-h7fw is a high-severity (CVSS 8.9) CWE-345 vulnerability in dnsjava:dnsjava. A fix is available for dnsjava:dnsjava — see the affected versions and patch details below.
DNSJava DNSSEC Bypass
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-cfxw-4h78-h7fw.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-cfxw-4h78-h7fw plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
dnsjava:dnsjavaReal-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
Records in DNS replies are not checked for their relevance to the query, allowing an attacker to respond with RRs from different zones.
Details
DNS Messages are not authenticated. They do not guarantee that
- received RRs are authentic
- not received RRs do not exist
- all or any received records in a response relate to the request
Applications utilizing DNSSEC generally expect these guarantees to be met, however DNSSEC by itself only guarantees the first two. To meet the third guarantee, resolvers generally follow an (undocumented, as far as RFCs go) algorithm such as: (simplified, e.g. lacks DNSSEC validation!)
- denote by
QNAMEthe name you are querying (e.g. fraunhofer.de.), and initialize a list of aliases - if the ANSWER section contains a valid PTR RRSet for
QNAME, return it (and optionally return the list of aliases as well) - if the ANSWER section contains a valid CNAME RRSet for
QNAME, add it to the list of aliases. SetQNAMEto the CNAME's target and go to 2. - Verify that
QNAMEdoes not have any PTR, CNAME and DNAME records using valid NSEC or NSEC3 records. Returnnull.
Note that this algorithm relies on NSEC records and thus requires a considerable portion of the DNSSEC specifications to be implemented. For this reason, it cannot be performed by a DNS client (aka application) and is typically performed as part of the resolver logic.
dnsjava does not implement a comparable algorithm, and the provided APIs instead return either
- the received DNS message itself (e.g. when using a ValidatingResolver such as in this example), or
- essentially just the contents of its ANSWER section (e.g. when using a LookupSession such as in this example)
If applications blindly filter the received results for RRs of the desired record type (as seems to be typical usage for dnsjava), a rogue recursive resolver or (on UDP/TCP connections) a network attacker can
- In addition to the actual DNS response, add RRs irrelevant to the query but of the right datatype, e.g. from another zone, as long as that zone is correctly using DNSSEC, or
- completely exchange the relevant response records
Impact
DNS(SEC) libraries are usually used as part of a larger security framework. Therefore, the main misuses of this vulnerability concern application code, which might take the returned records as authentic answers to the request. Here are three concrete examples of where this might be detrimental:
- RFC 6186 specifies that to connect to an IMAP server for a user, a mail user agent should retrieve certain SRV records and send the user's credentials to the specified servers. Exchanging the SRV records can be a tool to redirect the credentials.
- When delivering mail via SMTP, MX records determine where to deliver the mails to. Exchanging the MX records might lead to information disclosure. Additionally, an exchange of TLSA records might allow attackers to intercept TLS traffic.
- Some research projects like LIGHTest are trying to manage CA trust stores via URI and SMIMEA records in the DNS. Exchanging these allows manipulating the root of trust for dependent applications.
Mitigations
At this point, the following mitigations are recommended:
- When using a ValidatingResolver, ignore any Server indications of whether or not data was available (e.g. NXDOMAIN, NODATA, ...).
- For APIs returning RRs from DNS responses, filter the RRs using an algorithm such as the one above. This includes e.g.
LookupSession.lookupAsync. - Remove APIs dealing with raw DNS messages from the examples section or place a noticable warning above.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | dnsjava:dnsjava | all versions | 3.6.0dnsjava:dnsjava:3.6.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dnsjava:dnsjava, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update dnsjava:dnsjava to 3.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cfxw-4h78-h7fw 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-cfxw-4h78-h7fw can be triaged on real exposure rather than presence alone.
Tailored to GHSA-cfxw-4h78-h7fw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-cfxw-4h78-h7fw in your dependencies?
O3 Security finds GHSA-cfxw-4h78-h7fw across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.