How severe is CVE-2025-27513?

CVE-2025-27513 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-27513?

CVE-2025-27513 affects the following packages: OpenTelemetry.Api (NuGet), OpenTelemetry.Api (NuGet), OpenTelemetry.Api (NuGet), OpenTelemetry.Api (NuGet), OpenTelemetry.Api (NuGet). Ecosystems affected: NuGet.

How do I fix CVE-2025-27513?

Update OpenTelemetry.Api to 1.11.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-27513 is resolved across your whole dependency graph.

How do I detect CVE-2025-27513 in my NuGet dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for OpenTelemetry.Api, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-27513 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2025-27513 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-27513 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-27513?

CVE-2025-27513 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 44th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-27513?

CVE-2025-27513 is classified as CWE-770 (CWE-770). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-27513 published, and has it been updated?

CVE-2025-27513 was published on March 5, 2025 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

.NET

.NET NuGet

Not in CISA KEV

HIGH severity

CVE-2025-27513 — OpenTelemetry.Api

HIGHFix: open-telemetry/opentelemetry-dotnet@1b555c1

CVE-2025-27513 is a high-severity (CVSS 7.5) CWE-770 vulnerability in OpenTelemetry.Api. A fix is available for OpenTelemetry.Api — see the affected versions and patch details below.

OpenTelemetry .NET has a Denial of Service (DoS) Vulnerability in API Package

Also known asGHSA-8785-wc3w-h8q6

Published

Mar 5, 2025

Updated

Oct 28, 2026

Affected

5 pkgs

Patched

1 / 5

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-27513.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs44th percentile — riskier than 44% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

5 pkgs affected

.NETOpenTelemetry.Api.NETOpenTelemetry.Api.NETOpenTelemetry.Api.NETOpenTelemetry.Api.NETOpenTelemetry.Api

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

Impact

What kind of vulnerability is it? Who is impacted?

A vulnerability in OpenTelemetry.Api package 1.10.0 to 1.11.1 could cause a Denial of Service (DoS) when a tracestate and traceparent header is received.

Even if an application does not explicitly use trace context propagation, receiving these headers can still trigger high CPU usage.
This issue impacts any application accessible over the web or backend services that process HTTP requests containing a tracestate header.
Application may experience excessive resource consumption, leading to increased latency, degraded performance, or downtime.

Patches

Has the problem been patched? What versions should users upgrade to?

This issue has been resolved in OpenTelemetry.Api 1.11.2 by reverting the change that introduced the problematic behavior in versions 1.10.0 to 1.11.1.</li><li data-start="1290" data-end="1409">The fix ensures that valid tracing headers no longer cause excessive CPU consumption when received in requests.</li></ul><h4 data-start="1411" data-end="1434">Fixed Version:</h4>

OpenTelemetry .NET Version	Status
<= 1.9.x	✅ Not affected
1.10.0 - 1.11.1	❌ Vulnerable
1.11.2 (Fixed)	✅ Safe to use

Upgrade Command:

dotnet add package OpenTelemetry --version 1.11.2

Delisting of Affected Packages To prevent accidental usage, we have delisted the affected versions (1.10.0 to 1.11.1) from NuGet. Users should avoid these versions and upgrade to 1.11.2 immediately.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

References

Are there any links users can visit to find out more?

Affected Packages

5 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`OpenTelemetry.Api`	≥ 1.11.0&&< 1.11.2	1.11.2`dotnet add package OpenTelemetry.Api --version 1.11.2`
.NETNuGet	`OpenTelemetry.Api`	all versions	No fix
.NETNuGet	`OpenTelemetry.Api`	all versions	No fix
.NETNuGet	`OpenTelemetry.Api`	all versions	No fix
.NETNuGet	`OpenTelemetry.Api`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for OpenTelemetry.Api, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update OpenTelemetry.Api to 1.11.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-27513 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact _What kind of vulnerability is it? Who is impacted?_ A vulnerability in `OpenTelemetry.Api` package `1.10.0` to `1.11.1` could cause a Denial of Service (DoS) when a `tracestate` and `traceparent` header is received. * Even if an application does not explicitly use trace context propagation, receiving these headers can still trigger high CPU usage. * This issue impacts any application accessible over the web or backend services that process HTTP requests containing a `tracestate` header. * Application may experience excessive resource consumption, leading to increased latency, deg