How severe is CVE-2025-55315?

CVE-2025-55315 has a CVSS score of 9.9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-55315?

CVE-2025-55315 affects the following packages: Microsoft.AspNetCore.Server.Kestrel.Core (NuGet), Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet), Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet), Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet), Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet), Microsoft.AspNetCore.App.Runtime.linux-musl-x64 (NuGet), Microsoft.AspNetCore.App.Runtime.linux-x64 (NuGet), Microsoft.AspNetCore.App.Runtime.osx-arm64 (NuGet), and 29 more. Ecosystems affected: NuGet.

How do I fix CVE-2025-55315?

Update Microsoft.AspNetCore.Server.Kestrel.Core to 2.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-55315 is resolved across your whole dependency graph.

How do I detect CVE-2025-55315 in my NuGet dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.Server.Kestrel.Core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2025-55315 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2025-55315?

O3 pinpoints whether CVE-2025-55315 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2025-55315 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2025-55315, including 1 documented proof-of-concept exploit on Exploit-DB. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2025-55315?

CVE-2025-55315 has an EPSS (Exploit Prediction Scoring System) score of 66.3%, placing it in the 99th 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. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2025-55315?

CVE-2025-55315 is classified as CWE-444 (CWE-444). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-55315 published, and has it been updated?

CVE-2025-55315 was published on October 14, 2025 and was last updated on April 10, 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 NuGet

CVE-2025-55315

CRITICAL

Microsoft Security Advisory CVE-2025-55315: .NET Security Feature Bypass Vulnerability

Also known asBIT-aspnet-core-2025-55315GHSA-5rrx-jjjq-q2r5

Published

Oct 14, 2025

Updated

Apr 10, 2026

Affected

37 pkgs

Patched

37 / 37

Exploits

3 known

EPSS Exploitation Probability

via FIRST.org ↗

66.3%probability of exploitation in next 30 days

High Risk99th percentile+64.58%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

37 pkgs affected

.NETMicrosoft.AspNetCore.Server.Kestrel.Core.NETMicrosoft.AspNetCore.App.Runtime.linux-arm.NETMicrosoft.AspNetCore.App.Runtime.linux-arm64.NETMicrosoft.AspNetCore.App.Runtime.linux-musl-arm.NETMicrosoft.AspNetCore.App.Runtime.linux-musl-arm64.NETMicrosoft.AspNetCore.App.Runtime.linux-musl-x64.NETMicrosoft.AspNetCore.App.Runtime.linux-x64.NETMicrosoft.AspNetCore.App.Runtime.osx-arm64+29 more

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

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

Affected Packages

37 total 37 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`Microsoft.AspNetCore.Server.Kestrel.Core`	all versions	2.3.6
.NETNuGet	`Microsoft.AspNetCore.App.Runtime.linux-arm`	≥ 10.0.0-rc.1.25451.107&&< 10.0.0-rc.2.25502.107	10.0.0-rc.2.25502.107
.NETNuGet	`Microsoft.AspNetCore.App.Runtime.linux-arm64`	≥ 10.0.0-rc.1.25451.107&&< 10.0.0-rc.2.25502.107	10.0.0-rc.2.25502.107
.NETNuGet	`Microsoft.AspNetCore.App.Runtime.linux-musl-arm`	≥ 10.0.0-rc.1.25451.107&&< 10.0.0-rc.2.25502.107	10.0.0-rc.2.25502.107
.NETNuGet	`Microsoft.AspNetCore.App.Runtime.linux-musl-arm64`	≥ 10.0.0-rc.1.25451.107&&< 10.0.0-rc.2.25502.107	10.0.0-rc.2.25502.107
.NETNuGet	`Microsoft.AspNetCore.App.Runtime.linux-musl-x64`	≥ 10.0.0-rc.1.25451.107&&< 10.0.0-rc.2.25502.107	10.0.0-rc.2.25502.107

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-52492webappsmultiple

ASP.net 8.0.10 - Bypass

by Mohammed Idrees Banyamer · Apr 6, 2026

Exploit-DB Source

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.Server.Kestrel.Core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update Microsoft.AspNetCore.Server.Kestrel.Core to 2.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-55315 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-55315 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2025-55315. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

O3 Security · Impact-Aware SCA

Is CVE-2025-55315 in your dependencies?

O3 detects CVE-2025-55315 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works