{"id":"CVE-2026-42348","aliases":["GHSA-w2jh-77fq-7gp8"],"url":"https://o3.security/vulnerability/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)","published":"2026-05-12T18:01:41.812Z","modified":"2026-09-23T03:45:24.888192604Z","cvss":{"score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00311,"percentile":0.23717,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"NuGet","name":"OpenTelemetry.OpAmp.Client","fixedVersion":"0.2.0-alpha.1"}],"fix":{"url":"https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116","label":"open-telemetry/opentelemetry-dotnet-contrib#4116"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42348.json"},{"type":"ADVISORY","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":"FIX","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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-23T03:45:24.888192604Z"}}