CVE-2026-42348

OpAMP client reads unbounded HTTP response bodies

Published May 12, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

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.

Analysis

Technical impact

The OpAMP client, used by OpenTelemetry .NET, reads HTTP responses without imposing any upper bound on the size of the response body. An attacker who can control the OpAMP server or perform a man‑in‑the‑middle attack can cause the client to allocate an arbitrarily large buffer, leading to excessive memory consumption and potential application failure. This vulnerability is classified as CWE‑789 (Uncontrolled Memory Allocation).

Affected Systems

OpenTelemetry .NET OpAMP client, part of the OpenTelemetry dotnet contrib library. Versions before 0.2.0‑alpha.1 are affected; the fix is incorporated in 0.2.0‑alpha.1 and later releases.

Risk and Exploitability

The CVSS score of 5.9 indicates moderate severity, and no EPSS information is available. The vulnerability is not listed in the CISA KEV catalog. Attackers can exploit the flaw by directing an application to an attacker‑controlled OpAMP server or by intercepting traffic and injecting a large HTTP body. Successful exploitation can exhaust application memory and cause a crash or unresponsiveness, resulting in a denial‑of‑service condition for any users of the application.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

open-telemetry

opentelemetry-dotnet-contrib

affected

Version	Status	Constraints
`< 0.2.0-alpha.1`	affected	—

Configuration 1 [-]

cpe:2.3:a:opentelemetry:opentelemetry.opamp.client:*:*:*:*:*:.net:*:*

No data.

Vendor Product Versions

Opentelemetry

Opentelemetry-dotnet-contrib

Version	Status	Scheme	Platform
`[0,0.2.0-alpha.1)`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the OpenTelemetry dotnet contrib library to version 0.2.0‑alpha.1 or newer to apply the memory‑allocation fix
If upgrading is not immediately possible, restrict network connectivity to trusted OpAMP servers or block the OpAMP port from untrusted networks to mitigate the risk of malicious responses
Monitor application memory usage and log the size of OpAMP responses; investigate any unusually large responses to prevent or detect exploitation attempts

Generated by OpenCVE AI on May 12, 2026 at 19:38 UTC.

Tracking

Advisories

Source	ID	Title
Github GHSA	GHSA-w2jh-77fq-7gp8	OpAMP client reads unbounded HTTP response bodies

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.311% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

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

History

May 27, 2026 4:00 PM First appearance in the feed. Affected versions updated. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Opentelemetry opentelemetry.opamp.client
CPEs		cpe:2.3:a:opentelemetry:opentelemetry.opamp.client::::::.net::*
Vendors & Products		Opentelemetry opentelemetry.opamp.client

May 13, 2026 8:15 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

May 12, 2026 11:45 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Opentelemetry Opentelemetry opentelemetry-dotnet-contrib
Vendors & Products		Opentelemetry Opentelemetry opentelemetry-dotnet-contrib

May 12, 2026 6:15 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
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.
Title		OpAMP client reads unbounded HTTP response bodies
Weaknesses		CWE-789
References		https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4116 https://github.com/open-telemetry/opentelemetry-dotnet-contrib/security/advisories/GHSA-w2jh-77fq-7gp8
Metrics		cvssV3_1 `{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}`