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CVE-2026-42348 medium CVSS 5.9

Vulnerability in OpenTelemetry.OpAmp.Client (CVE-2026-42348)

Summary

Vulnerability in OpenTelemetry.OpAmp.Client (CVE-2026-42348). Risk of unauthorized operations or information disclosure. Exploitable via ReadAsByteArrayAsync. Mitigation: upgrade to 0.2.0-alpha.1 or later.

Original description

The description as published by the source.

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](ht…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-42348 has been found in OpenTelemetry.OpAmp.Client.
Attackers can target a specific entry point like ReadAsByteArrayAsync over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.9/10.
What to do: upgrade OpenTelemetry.OpAmp.Client to 0.2.0-alpha.1 or later.
If unsure, ask your IT team or search "OpenTelemetry.OpAmp.Client CVE-2026-42348" on the vendor's site.

CVE-2026-42348 (OpenTelemetry.OpAmp.Client) — CWE-789 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: ReadAsByteArrayAsync / HttpResponseMessage.Content
Patched: 0.2.0-alpha.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-789) exists in OpenTelemetry.OpAmp.Client. Attackers reach the vulnerable code path via ReadAsByteArrayAsync without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of OpenTelemetry.OpAmp.Client. Attack surface: ReadAsByteArrayAsync / HttpResponseMessage.Content.

🔥 Severity

Severity: Medium (CVSS 5.9/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.2.0-alpha.1.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'OpenTelemetry.OpAmp.Client' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'OpenTelemetry.OpAmp.Client' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で OpenTelemetry.OpAmp.Client を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade OpenTelemetry.OpAmp.Client to 0.2.0-alpha.1

    ステージング環境で 0.2.0-alpha.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

nuget OpenTelemetry.OpAmp.Client
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.2.0-alpha.1"}]}]

References

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