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OpenTelemetry dotnet: OTLP exporter reads unbounded HTTP response bodies

Collected exploitation and prediction evidence

Risk source coverage

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

CVE-2026-40182

Exact risk observation. Current source statements above are a separate evidence layer. Latest risk evidence.

No KEV entry is attached to this observation; this is not evidence that exploitation is absent.

FIRST EPSS: 0.30 % · percentile 23.00 % · scored 25 Oct 2026. Retained older prediction.

Observed 25 Oct 2026 15:18:41 UTC · Complete immutable risk JSON

cve-program · CVE-2026-40182

Published

OpenTelemetry dotnet is a dotnet telemetry framework. From 1.13.1 to before 1.15.2, When exporting telemetry to a back-end/collector over gRPC or HTTP using OpenTelemetry Protocol format (OTLP), if the request results in a unsuccessful request (i.e. HTTP 4xx or 5xx), the response is read into memory with no upper-bound on the number of bytes consumed. This could cause memory exhaustion in the consuming application if the configured back-end/collector endpoint is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response. This vulnerability is fixed in 1.15.2.

Source published
23 Apr 2026 17:51:34 UTC
Source modified
23 Apr 2026 18:38:57 UTC
Observed here
23 Oct 2026 15:48:27 UTC
Source terms
CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 5.3 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

euvd · EUVD-2026-25266

Published

OpenTelemetry dotnet is a dotnet telemetry framework. From 1.13.1 to before 1.15.2, When exporting telemetry to a back-end/collector over gRPC or HTTP using OpenTelemetry Protocol format (OTLP), if the request results in a unsuccessful request (i.e. HTTP 4xx or 5xx), the response is read into memory with no upper-bound on the number of bytes consumed. This could cause memory exhaustion in the consuming application if the configured back-end/collector endpoint is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response. This vulnerability is fixed in 1.15.2.

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Apr 23, 2026, 5:51:34 PM

dateUpdated: Apr 23, 2026, 6:38:57 PM

Source published
Apr 23, 2026, 5:51:34 PM (timezone not stated)
Source modified
Apr 23, 2026, 6:38:57 PM (timezone not stated)
Observed here
1 Nov 2026 06:15:31 UTC
Source terms
ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd · CVE-2026-40182

Published

OpenTelemetry dotnet is a dotnet telemetry framework. From 1.13.1 to before 1.15.2, When exporting telemetry to a back-end/collector over gRPC or HTTP using OpenTelemetry Protocol format (OTLP), if the request results in a unsuccessful request (i.e. HTTP 4xx or 5xx), the response is read into memory with no upper-bound on the number of bytes consumed. This could cause memory exhaustion in the consuming application if the configured back-end/collector endpoint is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response. This vulnerability is fixed in 1.15.2.

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Analyzed

Weakness classifications: CWE-789

Original publisher date fields

published: 2026-04-23T18:16:28.130

lastModified: 2026-10-26T22:10:00.163

1 source CPE criteria · context only
  • cpe:2.3:a:opentelemetry:opentelemetry:*:*:*:*:*:.net:*:*

The original JSON retains the logical configuration operators, exclusions and version bounds.

Source published
23 Apr 2026 18:16:28 UTC
Source modified
26 Oct 2026 22:10:00 UTC
Observed here
27 Oct 2026 10:09:56 UTC
Source terms
NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS 3.1 · [email protected] · Primary · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

osv · GHSA-q834-8qmm-v933

Published

### Summary When exporting telemetry to a back-end/collector over gRPC or HTTP using OpenTelemetry Protocol format (OTLP), if the request results in a unsuccessful request (i.e. HTTP 4xx or 5xx), the response is read into memory with no upper-bound on the number of bytes consumed. This could cause memory exhaustion in the consuming application if the configured back-end/collector endpoint is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response. ### Details https://github.com/open-telemetry/opentelemetry-dotnet/pull/6564 introduced a change to read the response body when a non-200 HTTP status code is received when exporting telemetry to aid debugging by operators so that the error response is included in the logs emitted by the exporter for both [gRPC](https://github.com/open-telemetry/opentelemetry-dotnet/blob/640cf63628567b76b348b26988920dbc0b5c1662/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpGrpcExportClient.cs#L123-L134) and [HTTP/protobuf](https://github.com/open-telemetry/opentelemetry-dotnet/blob/640cf63628567b76b348b26988920dbc0b5c1662/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpHttpExportClient.cs#L36-L41). An unintended consequence of this change is that the response body is [fully read into memory when received with no upper-bound](https://github.com/open-telemetry/opentelemetry-dotnet/blob/640cf63628567b76b348b26988920dbc0b5c1662/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpExportClient.cs#L68-L89). This vulnerability was surfaced during the investigation of GHSA-w8rr-5gcm-pp58. ### Impact If an application using the OTLP exporter is configured to use a back-end/collector endpoint that is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response the application could have its memory exhausted and create a denial-of-service condition. ### Mitigation The application's configured back-end/collector endpoint needs to behave maliciously. If the collector/back-end is a well-behaved implementation response bodies should not be excessively large if a request error occurs. ### Workarounds None known. ### Remediation [#7017](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7017) updates the OTLP exporter for both gRPC and HTTP to: - Limit the number of bytes read from the response body in an error condition to 4MiB (see https://github.com/open-telemetry/opentelemetry-proto/pull/781); - Only attempt to read the response body if OpenTelemetry error logging is enabled.

Source published
23 Apr 2026 21:26:10 UTC
Source modified
10 Sep 2026 03:51:02 UTC
Observed here
23 Oct 2026 16:01:25 UTC
Source terms
GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · MODERATE

ChangeIntel

An IT change radar: releases, security, known issues, retirements, documentation changes, and service status from public sources. Every item links to supporting evidence; dates and statuses can change after they are read.

Sources read 1 Nov 22:30 UTC · 275 of 275 readable · 272 fully read · documentation 469/469 current