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Fencer Vulns
medium 5.3

CVE-2026-40894 json

OpenTelemetry dotnet: Excessive memory allocation when parsing OpenTelemetry propagation headers

published 2026-04-23 6 mo ago modified 2026-10-26 13 d ago also GHSA-g94r-2vxg-569j , EUVD-2026-25269

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

OpenTelemetry dotnet is a dotnet telemetry framework. In OpenTelemetry.Api 0.5.0-beta.2 to 1.15.2 and OpenTelemetry.Extensions.Propagators 1.3.1 to 1.15.2, The implementation details of the baggage, B3 and Jaeger processing code in the OpenTelemetry.Api and OpenTelemetry.Extensions.Propagators NuGet packages can allocate excessive memory when parsing which could create a potential denial of service (DoS) in the consuming application. This vulnerability is fixed in 1.15.3.

Patch / fix

  • nuget OpenTelemetry.Api 1.15.3
  • nuget OpenTelemetry.Extensions.Propagators 1.15.3
  • opentelemetry opentelemetry 1.15.3
  • opentelemetry opentelemetry.api 1.15.3
  • opentelemetry opentelemetry.extensions.propagators 1.15.3

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
nuget OpenTelemetry.Api
>=0.5.0-beta.2, <1.15.3
1.15.3
nuget OpenTelemetry.Extensions.Propagators
>=1.3.1, <1.15.3
1.15.3

Affected products

  • open-telemetry opentelemetry-dotnet
  • open-telemetry OpenTelemetry.Api
  • open-telemetry OpenTelemetry.Extensions.Propagators

Classification

Weakness
  • CWE-789 Memory Allocation with Excessive Size Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.