CVE-2026-42348: 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
- #2926 - #4116 - CWE-789
Other sources
OpenTelemetry.OpAmp.Client is the OpAMP client for OpenTelemetry .NET. Prior to 0.2.0-alpha.1, 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. This vulnerability is fixed in 0.2.0-alpha.1.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-42348?
The severity of CVE-2026-42348 is high due to the potential for memory exhaustion in the consuming application.
How do I fix CVE-2026-42348?
To fix CVE-2026-42348, upgrade to the fixed version of OpenTelemetry.OpAmp.Client 0.2.0-alpha.1 or later.
What causes CVE-2026-42348?
CVE-2026-42348 is caused by the OpAMP client allocating an unbounded buffer for reading responses from the OpAMP server over HTTP.
Which versions of OpenTelemetry.OpAmp.Client are affected by CVE-2026-42348?
Versions of OpenTelemetry.OpAmp.Client prior to 0.2.0-alpha.1 are affected by CVE-2026-42348.
What is the impact of CVE-2026-42348?
The impact of CVE-2026-42348 is that it can lead to memory exhaustion in applications consuming responses from the OpAMP server.