---
title: "CVE-2025-55315: Microsoft Security Advisory CVE-2025-55315: .NET Security Feature Bypass Vulnerability"
url: https://erroneo.us/security/cve/CVE-2025-55315/
description: "CVE-2025-55315 (Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet)): Inconsistent interpretation of http requests ('http request/response smuggling') in…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-10-14
date_modified: 2026-02-22
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-55315"
kev: false
cvss: 9.9
epss: 0.66526
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** High exploit likelihood. EPSS ranks it in the top 5% of all CVEs for likely exploitation in the next 30 days. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 66.5% , percentile 99: FIRST’s model estimates a 66.5% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet) = 10.0.0-rc.1.25451.107, fixed in 10.0.0-rc.2.25502.107 ; Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet) = 10.0.0-rc.1.25451.107, fixed in 10.0.0-rc.2.25502.107 ; Microsoft.AspNetCore.App.Runtime.linux-musl-arm (NuGet) = 10.0.0-rc.1.25451.107, fixed in 10.0.0-rc.2.25502.107 ; Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 (NuGet) = 10.0.0-rc.1.25451.107, fixed in 10.0.0-rc.2.25502.107 . Check your lockfile, including transitive dependencies.

## What it is

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

- NuGet `Microsoft.AspNetCore.App.Runtime.linux-arm` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-arm64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-arm` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-arm64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-x64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-x64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.osx-arm64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.osx-x64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.win-arm` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.win-arm64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.win-x64` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.win-x86` = 10.0.0-rc.1.25451.107 → fixed: 10.0.0-rc.2.25502.107
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-arm` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-arm64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-arm` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-arm64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-x64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-x64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.osx-arm64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.osx-x64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.win-arm` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.win-arm64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.win-x64` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.win-x86` >= 9.0.0, <= 9.0.9 → fixed: 9.0.10
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-arm` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-arm64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-arm` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-arm64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-musl-x64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.linux-x64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.osx-arm64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.osx-x64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.win-arm` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.win-arm64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.win-x64` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.App.Runtime.win-x86` >= 8.0.0, <= 8.0.20 → fixed: 8.0.21
- NuGet `Microsoft.AspNetCore.Server.Kestrel.Core` <= 2.3.0 → fixed: 2.3.6

## Affected products (CVE record)

- Microsoft ASP.NET Core 2.3: 2.3 < 2.3.6
- Microsoft ASP.NET Core 8.0: 8.0 < 8.0.21
- Microsoft ASP.NET Core 9.0: 9.0 < 9.0.10
- Microsoft Microsoft Visual Studio 2022 version 17.10: 17.10.0 < 17.10.20
- Microsoft Microsoft Visual Studio 2022 version 17.12: 17.12.0 < 17.12.13
- Microsoft Microsoft Visual Studio 2022 version 17.14: 17.14.0 < 17.14.17

## Severity

- microsoft CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L/E:U/RL:O/RC:C`
- GitHub CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 66.53% probability of exploitation activity in the next 30 days; percentile 99.

## Sources

- [ASP.NET Security Feature Bypass Vulnerability](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-55315)
- [GitHub Advisory GHSA-5rrx-jjjq-q2r5](https://github.com/advisories/GHSA-5rrx-jjjq-q2r5)
- [CVE.org record CVE-2025-55315](https://www.cve.org/CVERecord?id=CVE-2025-55315)
- [NVD entry CVE-2025-55315](https://nvd.nist.gov/vuln/detail/CVE-2025-55315)
- [gist.github.com](https://gist.github.com/N3mes1s/d0897c13ca199e739ecc2b562f466040)
- [andrewlock.net](https://andrewlock.net/understanding-the-worst-dotnet-vulnerability-request-smuggling-and-cve-2025-55315/)
- [github.com](https://github.com/dotnet/aspnetcore/security/advisories/GHSA-5rrx-jjjq-q2r5)
- [github.com](https://github.com/dotnet/announcements/issues/371)

---
Source page: https://erroneo.us/security/cve/CVE-2025-55315/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt