OpAMP client reads unbounded HTTP response bodies
Summary
When receiving responses from the OpAMP server over HTTP, the OpAMP client allocates an unbounded buffer to read all bytes from the server, with no upper-bound on the number of bytes consumed.
This could cause memory exhaustion in the consuming application if the configured OpAMP server is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned in the response.
Details
#2926 introduced the initial HTTP transport components which uses ReadAsByteArrayAsync to copy the HttpResponseMessage.Content into a byte array. This code path allows an unbounded read of the entire HTTP response message.
Impact
If an application using the OpAMP client is configured to use an OpAMP server that is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned in the response, the application could have its memory exhausted and create a denial-of-service condition.
Mitigation
The application's configured OpAMP server needs to behave maliciously. If the OpAMP server is a well-behaved implementation, response bodies should not be excessively large.
Workarounds
None known.
Remediation
#4116 updates the OpAMP client HTTP transport to limit the maximum size of responses to 128KB.
Resources
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | OpenTelemetry.OpAmp.Client | < 0.2.0-alpha.1 | 0.2.0-alpha.1 |
References
- https://github.com/open-telemetry/opentelemetry-dotnet-contrib/security/advisories/GHSA-w2jh-77fq-7gp8
- https://nvd.nist.gov/vuln/detail/CVE-2026-42348
- https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116
- https://github.com/open-telemetry/opentelemetry-dotnet-contrib/commit/bf1fad4fa298ff451cda0efb0ee9c7a7eb46212a
- https://github.com/open-telemetry/opentelemetry-dotnet-contrib
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-789- Platform
- .NET (NuGet)
- Package
OpenTelemetry.OpAmp.Client- Disclosed
- 05.05.2026
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-w2jh-77fq-7gp8 - CC BY 4.0
Vulnerability history: OpenTelemetry.OpAmp.Client
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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