CVE-2023-41327 — wiremock-webhooks-extensi…
MEDIUMCVE-2023-41327 is a medium-severity (CVSS 4.6) Server-Side Request Forgery (SSRF) vulnerability in org.wiremock:wiremock-webhooks-extension. A fix is available for org.wiremock:wiremock-webhooks-extension — see the affected versions and patch details below.
Controlled SSRF through URL in the WireMock
Exploitation Status
No confirmed exploitation observed yet
- 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 CVE-2023-41327.
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
CVE-2023-41327 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 378,156 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
org.wiremock:wiremock-webhooks-extension☕org.wiremock:wiremock-webhooks-extensionReal-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
Impact
WireMock can be configured to only permit proxying (and therefore recording) to certain addresses. This is achieved via a list of allowed address rules and a list of denied address rules, where the allowed list is evaluated first. Documentation.
Until WireMock Webhooks Extension 3.0.0-beta-15, the filtering of target addresses from the proxy mode DID NOT work for Webhooks, so the users were potentially vulnerable regardless of the limitProxyTargets settings.
Via the WireMock webhooks configuration, POST requests from a webhook might be forwarded to an arbitrary service reachable from WireMock’s instance. For example, If someone is running the WireMock docker Container inside a private cluster, they can trigger internal POST requests against unsecured APIs or even against secure ones by passing a token, discovered using another exploit, via authentication headers.
Affected components
- WireMock Webhooks Extension 2.x versions until 2.35.1 (security patch)
- WireMock 3.x version until 3.0.3 (security patch)
- All versions of WireMock Studio (discontinued). This distribution bundles the WireMock Webhooks Extension and activates it by default
Patches and Mitigation
- For WireMock 2.x and 3.x - upgrade to the versions with the security patches
- Setup network restrictions similarly to https://wiremock.org/docs/configuration/#preventing-proxying-to-and-recording-from-specific-target-addresses
- For WireMock Studio: Stop using discontinued WireMock Studio, migrate to other distributions. The vendor of WireMock Studio recommends migration to WireMock Cloud
NOTE: It was confirmed that WireMock Cloud does not expose sensitive internal APIs and hence not vulnerable to the issue. No action is needed if you use this SaaS distribution.
Workarounds
- Use external firewall rules to define the list of permitted destinations
References
Credits
- @W0rty for reporting CVE-2023-39967 in WireMock Studio
- WireMock Inc. team for discovering similar exploits in Webhooks and the risk in the Proxy mode defaults for WireMock
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.wiremock:wiremock-webhooks-extension | ≥ 3.0.0&&< 3.0.3 | 3.0.3org.wiremock:wiremock-webhooks-extension:3.0.3 |
| ☕Maven | org.wiremock:wiremock-webhooks-extension | ≥ 2.0.0&&< 2.35.1 | 2.35.1org.wiremock:wiremock-webhooks-extension:2.35.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.wiremock:wiremock-webhooks-extension, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.wiremock:wiremock-webhooks-extension to 3.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-41327 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 CVE-2023-41327 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-41327. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-41327 in your dependencies?
O3 Security finds CVE-2023-41327 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.