Summary
WireMock Controlled Server Side Request Forgery vulnerability through URL
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
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.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2023-41327 has a CVSS score of 4.6 (Medium). The vector is reachable from an adjacent network, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.0.3, 2.35.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
org.wiremock:wiremock-webhooks-extension to 3.0.3 or later; org.wiremock:wiremock-webhooks-extension to 2.35.1 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2023-41327? CVE-2023-41327 is a medium-severity server-side request forgery (SSRF) vulnerability in org.wiremock:wiremock-webhooks-extension (maven), affecting versions >= 3.0.0, < 3.0.3. It is fixed in 3.0.3, 2.35.1. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2023-41327? CVE-2023-41327 has a CVSS score of 4.6 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of org.wiremock:wiremock-webhooks-extension are affected by CVE-2023-41327? org.wiremock:wiremock-webhooks-extension (maven) versions >= 3.0.0, < 3.0.3 is affected.
- Is there a fix for CVE-2023-41327? Yes. CVE-2023-41327 is fixed in 3.0.3, 2.35.1. Upgrade to this version or later.
- Is CVE-2023-41327 exploitable, and should I be worried? Whether CVE-2023-41327 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-41327 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-41327?
- Upgrade
org.wiremock:wiremock-webhooks-extensionto 3.0.3 or later - Upgrade
org.wiremock:wiremock-webhooks-extensionto 2.35.1 or later
- Upgrade