GHSA-wfr5-454p-mjc2 — OpenTelemetry.Exporter.In…
MEDIUMGHSA-wfr5-454p-mjc2 is a medium-severity (CVSS 6.5) CWE-295 vulnerability in OpenTelemetry.Exporter.Instana. A fix is available for OpenTelemetry.Exporter.Instana — see the affected versions and patch details below.
OpenTelemetry.Exporter.Instana bypasses TLS certificate validation when a proxy is configured
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 GHSA-wfr5-454p-mjc2.
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-wfr5-454p-mjc2 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 378,567 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
OpenTelemetry.Exporter.InstanaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The OpenTelemetry.Exporter.Instana NuGet package does not validate HTTPS/TLS certificates are valid when sending telemetry to a configured Instana back-end when a proxy is configured using the INSTANA_ENDPOINT_PROXY environment variable.
If a network attacker can Man-in-the-Middle (MitM) the proxy connection, all OpenTelemetry telemetry data and the Instana API key are exposed to the attacker.
Details
The Transport.ConfigureBackendClient() method creates an HttpClient instance that completely disables TLS server certificate validation if the INSTANA_ENDPOINT_PROXY is configured with a valid proxy URL with no ability to re-enable it.
Impact
If the configured proxy is attacker-controlled (or a network attacker MitM the connection), or if it is possible for the process' configuration to be changed to add an attacker-provided value for INSTANA_ENDPOINT_PROXY then all Instana telemetry could be read by an unauthorized party and the service's Instana API key compromised, potentially before being forwarded to Instana presenting no noticeable loss of telemetry data without a valid TLS server certificate being presented to the client that matches the expected hostname or IP address.
Mitigation
The proxy configured by the INSTANA_ENDPOINT_PROXY environment variable must be malicious or be possible to be subject to a MitM attack.
Workarounds
Do not configure the INSTANA_ENDPOINT_PROXY environment variable.
Remediation
#4153 refactors HttpClient creation so that TLS certificate validation is no longer disabled by default when using a proxy.
In environments where this capability is required, for example for local development, the previous behaviour can be restored using the `` option:
builder.AddInstanaExporter((options) =>
{
options.HttpClientFactory = () =>
{
var handler = new HttpClientHandler()
{
#if NET
ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator,
#else
ServerCertificateCustomValidationCallback = static (_, _, _, _) => true,
#endif
};
return new HttpClient(handler, disposeHandler: true);
};
});
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | OpenTelemetry.Exporter.Instana | all versions | 1.1.0dotnet add package OpenTelemetry.Exporter.Instana --version 1.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for OpenTelemetry.Exporter.Instana, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update OpenTelemetry.Exporter.Instana to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wfr5-454p-mjc2 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-wfr5-454p-mjc2 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-wfr5-454p-mjc2. 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-wfr5-454p-mjc2 in your dependencies?
O3 Security finds GHSA-wfr5-454p-mjc2 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.