Telemetry disclosure and injection via shared temp directory
Published May 12, 2026 · Updated May 12, 2026
Improper temporary-file handling in OpenTelemetry .NET 1.8.0 through 1.15.2 allows local users to read or inject OTLP retry blobs. With disk retry enabled but no directory configured, the exporter uses Path.GetTempPath() and scans fixed traces, metrics, and logs subdirectories for *.blob files. Exploitation requires access to a shared process temporary directory and can expose telemetry, forward forged telemetry under the application's identity, or consume disk and retry-loop resources.
Summary
What happened
Improper temporary-file handling in OpenTelemetry .NET 1.8.0 through 1.15.2 allows local users to read or inject OTLP retry blobs. With disk retry enabled but no directory configured, the exporter uses Path.GetTempPath() and scans fixed traces, metrics, and logs subdirectories for *.blob files. Exploitation requires access to a shared process temporary directory and can expose telemetry, forward forged telemetry under the application's identity, or consume disk and retry-loop resources.
The record
- CVE
- CVE-2026-42191
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- OpenTelemetry
- Product
- OpenTelemetry .NET
- Classifications
- CWE-379, T1565.002
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 1.8.0, < 1.15.3
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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