CVE-2026-40891

What it is

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.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. High risk of service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-23 18:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-26 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 5.3 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-04-23 18:16 UTC

Last modified

2026-10-26 21:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-789

Record status

Analyzed

Affected

• Opentelemetry < 1.15.3

Attack profile CVSS 3.1 · 5.3

Attack vector

Adjacent network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-40891.md and follow it. Check whether this project is affected by CVE-2026-40891. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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