CVE-2026-42348: OpenTelemetry.OpAmp.Client OpAMP Client Reads Unbounded HTTP Vulnerability
MODERATECVE-2026-42348 is a MODERATE (CVSS 5.9) opamp client reads unbounded http vulnerability (CWE-789: Memory Allocation with Excessive Size Value) affecting OpenTelemetry.OpAmp.Client libraries in the NuGet ecosystem. The issue involves opamp client reads unbounded http response bodies. Remediation is available by upgrading affected packages to version 0.2.0-alpha.1.
CVE-2026-42348 at a Glance
Security Impact
CVSS: 5.9
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).
How to Fix CVE-2026-42348
To remediate this vulnerability, upgrade all affected OpenTelemetry.OpAmp.Client dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade OpenTelemetry.OpAmp.Client to 0.2.0-alpha.1Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for OpenTelemetry.OpAmp.ClientHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-42348, inspect your project dependencies for OpenTelemetry.OpAmp.Client:
inspect dependencies for OpenTelemetry.OpAmp.ClientAnalyze the terminal output to locate any version of OpenTelemetry.OpAmp.Client in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.2.0-alpha.1), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-789: Memory Allocation with Excessive Size Value, where the product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. In OpenTelemetry.OpAmp.Client, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-42348 Affected OpenTelemetry.OpAmp.Client Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
OpenTelemetry.OpAmp.Client
|
NuGet |
< 0.2.0-alpha.1
|
0.2.0-alpha.1
|
References
Frequently Asked Questions
What is CVE-2026-42348?
Which OpenTelemetry.OpAmp.Client versions are affected?
What version fixes CVE-2026-42348?
Is OpenTelemetry.OpAmp.Client affected?
What is the CVSS score of CVE-2026-42348?
What CWE is associated with CVE-2026-42348?
How can I check NuGet dependencies for CVE-2026-42348?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-w2jh-77fq-7gp8",
"modified" : "2026-05-13T16:27:09Z",
"published" : "2026-05-05T21:57:54Z",
"aliases" : [ "CVE-2026-42348" ],
"summary" : "OpAMP client reads unbounded HTTP response bodies",
"details" : "### Summary\n\nWhen 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.\n\nThis 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. \n\n### Details\n\n[#2926](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/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.\n\n### Impact\n\nIf 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.\n\n### Mitigation\n\nThe 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.\n\n### Workarounds\n\nNone known.\n\n### Remediation\n\n[#4116](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116) updates the OpAMP client HTTP transport to limit the maximum size of responses to 128KB.\n\n### Resources\n\n- [#2926](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/2926)\n- [#4116](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116)\n- [CWE-789](https://cwe.mitre.org/data/definitions/789.html)",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "NuGet",
"name" : "OpenTelemetry.OpAmp.Client"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "0.2.0-alpha.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/open-telemetry/opentelemetry-dotnet-contrib/security/advisories/GHSA-w2jh-77fq-7gp8"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42348"
}, {
"type" : "WEB",
"url" : "https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116"
}, {
"type" : "WEB",
"url" : "https://github.com/open-telemetry/opentelemetry-dotnet-contrib/commit/bf1fad4fa298ff451cda0efb0ee9c7a7eb46212a"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/open-telemetry/opentelemetry-dotnet-contrib"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-789" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2026-05-05T21:57:54Z",
"nvd_published_at" : "2026-05-12T18:17:24Z"
}
}