CVE-2026-40891: open-telemetry opentelemetry-dotnet
Vulnerability summary
CVE-2026-40891 is a medium (CVSS 5.3) vulnerability in open-telemetry opentelemetry-dotnet. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 19.9% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 0 · Related 1Timeline
- 23-04-2026PublishedVulnerability first disclosed.
- 23-04-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
5 scores · 5 sources · 1 version- OSV · WolfiEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · ChainguardEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · NugetEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST5.3MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.29%
Chance of exploitation in the next 30 days
Percentile
20%
Versus all other CVEs
30-day change
+0.10 pp
From 0.19% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Chainguard2 products
- azure-functions-host< 4.1051.100-r0
- kubernetes-reflector< 10.0.39-r1
Open-telemetry2 products
- opentelemetry-dotnet≥ 1.13.1, < 1.15.3
- opentelemetry.exporter.opentelemetryprotocol≥ 1.13.1, < 1.15.3
NuGet1 product
- OpenTelemetry.Exporter.OpenTelemetryProtocol≥ 1.13.1, < 1.15.3
Opentelemetry1 product
- opentelemetry≥ 1.13.1, < 1.15.3
Wolfi1 product
- kubernetes-reflector< 10.0.39-r1
5 vendors · 7 products
References
6 links- github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-mr8r-92fq-pj8pX Refsource CONFIRMAdvisoryWEBMitigationVendor Advisory
