CVE-2026-69304
published 2026-09-08CVE-2026-69304: Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
PriorityP335medium5.9CVSS 3.1
AVNACHPRNUINSUCNINAH
EPSS
0.85%
58.1th percentile
Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
Affected
19 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | asp.net_core | — | — |
| microsoft | asp.net_core | — | — |
| microsoft | asp.net_core | >= 10.0.0 < 10.0.9 | 10.0.9 |
| microsoft | asp.net_core | >= 8.0.0 < 8.0.28 | 8.0.28 |
| microsoft | asp.net_core | >= 9.0.0 < 9.0.17 | 9.0.17 |
| microsoft | asp.net_core_10.0 | >= 10.0 < 10.0.12 | 10.0.12 |
| microsoft | asp.net_core_11.0 | >= 11.0 < 11.0 RC1 | 11.0 RC1 |
| microsoft | asp.net_core_8.0 | >= 8.0 < 8.0.31 | 8.0.31 |
| microsoft | asp.net_core_9.0 | >= 9.0 < 9.0.20 | 9.0.20 |
| microsoft | microsoft_visual_studio_2022_version_17.14 | >= 17.14.0 < 17.14.40 | 17.14.40 |
| microsoft | microsoft_visual_studio_2026_version_18.9 | >= 18.9.0 < 18.9.3 | 18.9.3 |
| microsoft | net | >= 10.0.0 < 10.0.12 | 10.0.12 |
| microsoft | net | >= 8.0.0 < 8.0.31 | 8.0.31 |
| microsoft | net | >= 9.0.0 < 9.0.20 | 9.0.20 |
| microsoft | net_10.0 | >= 10.0.0 < 10.0.12 | 10.0.12 |
| microsoft | net_8.0 | >= 8.0.0 < 8.0.31 | 8.0.31 |
| microsoft | net_9.0 | >= 9.0.0 < 9.0.20 | 9.0.20 |
| microsoft | visual_studio_2022 | >= 17.14.0 < 17.14.40 | 17.14.40 |
| microsoft | visual_studio_2026 | >= 18.9.0 < 18.9.3 | 18.9.3 |
CVSS provenance
nvdv3.15.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
ghsa5.9MEDIUM
vendor_redhat5.9MEDIUM
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Red Hat
dotnet: ASP.NET Core: Denial of Service via Data Amplification
vendor_redhat·2026-09-08·CVSS 5.9
CVE-2026-69304 [MEDIUM] CWE-409 dotnet: ASP.NET Core: Denial of Service via Data Amplification
dotnet: ASP.NET Core: Denial of Service via Data Amplification
Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
A flaw was found in ASP.NET Core. This vulnerability arises from the improper handling of highly compressed data, a technique referred to as data amplification. An unauthorized attacker can exploit this weakness remotely over a network. Successful exploitation leads to a denial of service, rendering the affected system inaccessible to legitimate users.
Package: dotnet10.0 (Red Hat Hardened Images) - Affected
Package: dotnet8.0 (Red Hat Hardened Images) - Affected
Package: dotnet9.0 (Red Hat Hardened Images) - Affected
GHSA
Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
ghsa·2026-09-09·CVSS 5.9
CVE-2026-69304 [MEDIUM] CWE-409 Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
# Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
## Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core IIS out-of-process hosting and request decompression. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
The IIS Middleware for ASP.NET Core did not properly constrain decompression of certain types of request, leading to excess memory consumption and a Denial of Service.
## Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/443
## CVSS Details
- **Version
GHSA
Duplicate Advisory: Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
ghsa·2026-09-08·CVSS 5.9
CVE-2026-69304 [MEDIUM] CWE-409 Duplicate Advisory: Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
Duplicate Advisory: Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability
### Duplicate Advisory
This advisory has been withdrawn because it is a duplicate of GHSA-8cp2-47hg-mfgh. This link is maintained to preserve external references.
### Original Description
Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
No detection rules found.
No public exploits indexed.
Sans Isc
September 2026 Microsoft Patch Tuesday, (Tue, Sep 8th)
blogs_sans_isc·2026-09-08·CVSS 7.8
CVE-2026-81963 [HIGH] September 2026 Microsoft Patch Tuesday, (Tue, Sep 8th)
September 2026 Microsoft Patch Tuesday
Published: 2026-09-08. Last Updated: 2026-09-08 19:20:30 UTC
by Johannes Ullrich (Version: 1)
0 comment(s)
This month, Microsoft released patches for a record-breaking 973 vulnerabilities, including 113 rated critical. It is by far the largest Patch Tuesday to date, well ahead of the previous high of 664 set in July 2026. Two vulnerabilities are listed as exploited in the wild, while none were publicly disclosed before Patch Tuesday. Notable fixes include Windows privilege escalation and critical RCEs in Skype for Business, MSMQ and RRAS.
A few vulnerabilities worth mentioning:
Windows Update Stack Elevation of Privilege Vulnerability (CVE-2026-81963)
Microsoft reports that CVE-2026-81963 is being exploited, though it was not publicly disclosed b
Rapid7
Patch Tuesday - September 2026
blogs_rapid7·2026-09-08·CVSS 7.8
CVE-2026-85880 [HIGH] Patch Tuesday - September 2026
Microsoft is publishing 974 own-product vulnerabilities on September 2026 Patch Tuesday , including 723 vulnerabilities in Windows. Along with Microsoft fixes for 25 non-Microsoft CVEs, that brings the total number of vulnerabilities on the table today to 999. Whether this is the biggest Patch Tuesday ever depends on how we count, but this is by far the most CVEs that Microsoft has ever published in a single day. As Rapid7 noted last month, there is no reason to suppose that Patch Tuesday will ever return to the lower volumes we saw prior to 2026. Microsoft is aware of exploitation in the wild for two of the vulnerabilities published today.
## Windows ALPC: zero-day EoP
The eternal game of elevation of privilege whack-a-mole between Microsoft and attackers continues. This month, the batt
Bugzilla
CVE-2026-69304 dotnet: ASP.NET Core: Denial of Service via Data Amplification
bugzilla·2026-09-08·CVSS 5.9
CVE-2026-69304 [MEDIUM] CVE-2026-69304 dotnet: ASP.NET Core: Denial of Service via Data Amplification
CVE-2026-69304 dotnet: ASP.NET Core: Denial of Service via Data Amplification
Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
2026-09-08
Published