CVE-2026-40891: OpenTelemetry dotnet is a dotnet telemetry framework

Routine

MEDIUM 5.3UPGRADE

CVE-2026-40891 is a medium-severity flaw (CVSS 5.3) affecting opentelemetry. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 d

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Adjacent network
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 91%)
CISA exploited list	No
Weakness	CWE-789
Published	2026-04-23
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: opentelemetry

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-23 18:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

opentelemetry opentelemetry UPGRADE

Affected: >= 1.13.1 and < 1.15.3

Fixed in: 1.15.3

Safe to downgrade to: a release before 1.13.1

1. Check installed version

apt-cache policy opentelemetry || rpm -q opentelemetry || opentelemetry --version

2. UPGRADE to 1.15.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade opentelemetry

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opentelemetry

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.13.1 (Debian / Ubuntu)

apt-cache madison opentelemetry sudo apt install opentelemetry=<VERSION_BEFORE_1.13.1> sudo apt-mark hold opentelemetry

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list opentelemetry sudo dnf downgrade opentelemetry-<VERSION_BEFORE_1.13.1> sudo dnf versionlock add opentelemetry

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40891?

opentelemetry: upgrade to 1.15.3. Exact commands for each OS are on this page.

Is CVE-2026-40891 being exploited?

CVE-2026-40891 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40891 affect?

CVE-2026-40891 affects opentelemetry. Severity is medium (CVSS 5.3). 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

How urgent is CVE-2026-40891?

Priority 21/100. No elevated risk signals yet.

Related CVEs

CVE-2026-40894 MEDIUM 5.3 UPGRADE UPGRADE OpenTelemetry dotnet is a dotnet telemetry framework
CVE-2026-40182 MEDIUM 5.3 UPGRADE OpenTelemetry dotnet is a dotnet telemetry framework
CVE-2026-41078 MEDIUM 5.9 UPGRADE OpenTelemetry dotnet is a dotnet telemetry framework
CVE-2026-44967 MEDIUM 5.3 UPGRADE OpenTelemetry-cpp is the C++ implementation of OpenTelemetry
CVE-2026-54285 MEDIUM 5.3 UPGRADE opentelemetry-js is the OpenTelemetry JavaScript Client

References

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