Vulnerability in OpenTelemetry.Exporter.OpenTelemetryProtocol (CVE-2026-42191)
Summary
Vulnerability in OpenTelemetry.Exporter.OpenTelemetryProtocol (CVE-2026-42191). Confidential information can be exposed externally. Exploitable via traces. Mitigation: upgrade to 1.15.3 or later.
Original description
The description as published by the source.
Summary
The OTLP disk retry feature in OpenTelemetry.Exporter.OpenTelemetryProtocol silently fell back to Path.GetTempPath() when OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY=disk was set but OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_DIRECTORY_PATH was not configured.
The exporter stored and loaded *.blob files under fixed, signal-named subdirectories (traces, metrics, logs) beneath that shared temporary root path.
On multi-user systems where the temporary directory is accessible to other local accounts, this exposed three attack surfaces:
- Blob injection (integrity): an attacker could write crafted
*.blobfiles into the predictable path; the exporter picks them up on the next retry cycle and forwards them to the configured OTLP endpoint under the application's identity. - Telemetry disclosure (confidentiality): an attacker reads
*.blobfiles written by the application between export failures, recovering encoded telemetry payloads (spans, metric data points, log records). - Resource exhaustion (availability): an attacker deposits numerous or oversized blob files, degrading retry-loop performance or consuming disk space.
Details
Preconditions
OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRYis set todisk.OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_DIRECTORY_PATHis not set, causing the exporter to resolve the blob storage root using theSystem.IO.Path.GetTempPath()API.- A local attacker has read or write access to the process' temp…
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-2026-42191 has been found in OpenTelemetry.Exporter.OpenTelemetryProtocol.
Attackers can target a specific entry point like traces over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.5/10.
What to do: upgrade OpenTelemetry.Exporter.OpenTelemetryProtocol to 1.15.3 or later.
If unsure, ask your IT team or search "OpenTelemetry.Exporter.OpenTelemetryProtocol CVE-2026-42191" on the vendor's site.
CVE-2026-42191 (OpenTelemetry.Exporter.OpenTelemetryProtocol) — CWE-379 / CVSS v3 6.5
Attack vector: local / no user interaction
Attack surface: traces / metrics / logs / OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY
Patched: 1.15.3 — 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.
A vulnerability (CWE-379) exists in OpenTelemetry.Exporter.OpenTelemetryProtocol. Attackers reach the vulnerable code path via traces.
Check the vendor advisory for the affected versions of OpenTelemetry.Exporter.OpenTelemetryProtocol. Attack surface: traces / metrics / logs / OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY.
Severity: Medium (CVSS 6.5/10). Confidential information can be exposed externally.
Update to 1.15.3.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'OpenTelemetry.Exporter.OpenTelemetryProtocol' . 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
-
1Identify exposure identify
grep -r 'OpenTelemetry.Exporter.OpenTelemetryProtocol' . | 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.Exporter.OpenTelemetryProtocolを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade OpenTelemetry.Exporter.OpenTelemetryProtocol to 1.15.3ステージング環境で 1.15.3 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。
-
3Post-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
References
- advisory nvd.nist.gov
- package github.com
- patch security-advisories@github.com
- patch security-advisories@github.com
- web github.com
- web github.com