Is CVE-2026-40891 in the CISA KEV catalog?

No. CVE-2026-40891 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40891?

CVE-2026-40891 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2026-40891?

CVE-2026-40891 has an EPSS score of 0.19% (9th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40891?

Upgrade opentelemetry to 1.15.3 or later.

CVE & CISA-KEV Catalog

CVE-2026-40891

MEDIUM

5.3

CVSS v3

NVD

Description

OpenTelemetry dotnet is a dotnet telemetry framework. From 1.13.1 to before 1.15.2, When exporting telemetry over gRPC using the OpenTelemetry Protocol (OTLP), the exporter may parse a server-provided grpc-status-details-bin trailer during retry handling. Prior to the fix, a malformed trailer could encode an extremely large length-delimited protobuf field which was used directly for allocation, allowing excessive memory allocation and potential denial of service (DoS). This vulnerability is fixed in 1.15.2.

CWE-789

How to fix

Remediation Available

opentelemetryNVD

Affected:>= 1.13.1, < 1.15.3Fixed in:1.15.3CVE-2026-40891derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

0.19%probability of exploitation in 30 days

9thpercentile

Low risk: more likely to be exploited than 9% of all known CVEs.

References

Patch2

Vendor Advisory1

github.com

Embed a live status badge for CVE-2026-40891

Markdown

[![CVE-2026-40891](https://tridentstack.com/cve/badge/CVE-2026-40891.svg)](https://tridentstack.com/cve/CVE-2026-40891)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-40891"><img src="https://tridentstack.com/cve/badge/CVE-2026-40891.svg" alt="CVE-2026-40891"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-29.