HOMEVULNERABILITIESCVE-2026-40891
MEDIUM

CVE-2026-40891

CWE-789Published: April 23, 2026· Updated: Apr 29, 2026

5.3
CVSS v3.1
EPSS:0.01%probability of exploitation in 30 daysPercentile:2.6th

Official 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.

NVD Source

Technical Analysis

CVE-2026-40891 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 5.3.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorAdjacent
Attack ComplexityHigh
Privileges Req.None
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

Affected Vendors & Products

opentelemetry1 product
opentelemetry
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/open-telemetry/opentelemetry-dotnet/pull/5980
PATCHhttps://github.com/open-telemetry/opentelemetry-dotnet/pull/7064
ADVISORYhttps://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-mr8r-92fq-pj8p

All References (3)

→
https://github.com/open-telemetry/opentelemetry-dotnet/pull/5980Issue Tracking · Patch
→
https://github.com/open-telemetry/opentelemetry-dotnet/pull/7064Issue Tracking · Patch
→
https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-mr8r-92fq-pj8pVendor Advisory · Mitigation

Quick Facts

CVE IDCVE-2026-40891
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-789
CISA KEVNo
EPSS (30d)0.01%
Affected1 vendor
PublishedApr 23, 2026

Related CVEs (CWE-789)

CVE-2026-28253
8.7
CVE-2026-20048
7.7
CVE-2021-47970
7.5
CVE-2026-35186
7.5
CVE-2026-33174
7.5
CVE-2026-24146
7.5

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-40891 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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