Cyber Resilience

CVE-2026-42191

Opentelemetry.Exporter.Opentelemetryprotocol 1.8.0 – 1.15.3

Published
12 May 2026
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
EPSS Score 0.0011 1th percentile
Risk Priority 42 floored blend · peak EPSS

Summary

CVE-2026-42191 is a medium-severity Creation of Temporary File in Directory with Insecure Permissions (CWE-379) vulnerability in Opentelemetry Opentelemetry.Exporter.Opentelemetryprotocol. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and SC-4 (Information in Shared System Resources) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

OpenTelemetry.Exporter.OpenTelemetryProtocol is the OTLP (OpenTelemetry Protocol) exporter implementation. From 1.8.0 to 1.15.2, 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…

more

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 allows an attacker to write crafted *.blob files, read *.blob files written by the application between export failures, or deposit numerous or oversized blob files, degrading retry-loop performance or consuming disk space. This vulnerability is fixed in 1.15.3.

CWE(s)
CWE-379

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1565.001 Stored Data Manipulation Impact
Adversaries may insert, delete, or manipulate data at rest in order to influence external outcomes or hide activity, thus threatening the integrity of the data.
attack.mitre.org →
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Why these techniques?

Insecure temp directory fallback enables local read of application data (T1005), stored data tampering via crafted blobs (T1565.001), and disk exhaustion DoS (T1499.004).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-44967Same vendor: Opentelemetry
CVE-2026-42348Same vendor: Opentelemetry
CVE-2026-39882Same vendor: Opentelemetry
CVE-2026-40894Same vendor: Opentelemetry
CVE-2026-45680Same vendor: Opentelemetry
CVE-2026-41310Same vendor: Opentelemetry
CVE-2026-45681Same vendor: Opentelemetry
CVE-2026-45678Same vendor: Opentelemetry
CVE-2026-41483Same vendor: Opentelemetry
CVE-2024-36129Same vendor: Opentelemetry

Affected Assets

opentelemetry
opentelemetry.exporter.opentelemetryprotocol
1.8.0 — 1.15.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • SC-4 Information in Shared System Resources
  • AC-6 Least Privilege
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 1 hardening rule · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)
  • V15.4.2

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match
prevent

Directly enforces access restrictions on files created in shared temporary directories, blocking unauthorized read/write of *.blob retry files by other local users.

SC-4 Information in Shared System Resources good match
prevent

Prevents unintended information transfer and manipulation via shared system resources (temp paths) when the disk-retry feature falls back to Path.GetTempPath().

AC-6 Least Privilege partial match
prevent

Limits process privileges so the exporter cannot create or access retry blobs in world-readable/writable temporary locations without explicit configuration.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent developers from writing code that creates temp files in insecure directories.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture principles include proper file-system permission models that mitigate insecure temp-file creation.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly require safe temporary-file creation with restrictive permissions.

A.8.3 Information access restriction partial match
mitigates

Information access restriction policies can limit who may read or list files in shared temporary directories.

A.8.9 Configuration management partial match
mitigates

Configuration management can enforce secure default permissions on temporary directories.

References