PatchTheCVECVE-2026-69304: Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attack
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MEDIUM 5.9REMOTEWATCHLISTUPGRADEUPGRADEUPGRADE
CVE-2026-69304 is a medium-severity flaw (CVSS 5.9) affecting asp.net core, visual studio 2022, visual studio 2026. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
Why this priority
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.9 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.9% (top 42%) |
| CISA exploited list | No |
| Weakness | CWE-409 |
| Published | 2026-09-08 |
| Last modified | 2026-09-30 |
Publisher (CNA): Microsoft Corporation · Vendor: microsoft
Last updated 2026-09-30 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
microsoft asp.net core UPGRADE
Affected: >= 8.0.0 and < 8.0.28 · >= 9.0.0 and < 9.0.17 · >= 10.0.0 and < 10.0.9 · > 11.0.0 · 11.0 rc1
Fixed in: 8.0.28, 9.0.17, 10.0.9
Safe to downgrade to: a release before 8.0.0
1. Check installed version
apt-cache policy asp.net-core || rpm -q asp.net-core || asp.net-core --version
2. UPGRADE to 8.0.28 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade asp.net-core
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade asp.net-core
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 8.0.0 (Debian / Ubuntu)
apt-cache madison asp.net-core
sudo apt install asp.net-core=<VERSION_BEFORE_8.0.0>
sudo apt-mark hold asp.net-core
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list asp.net-core
sudo dnf downgrade asp.net-core-<VERSION_BEFORE_8.0.0>
sudo dnf versionlock add asp.net-core
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
microsoft visual studio 2022 UPGRADE
Affected: >= 17.14.0 and < 17.14.40
Fixed in: 17.14.40
Safe to downgrade to: a release before 17.14.0
1. Check installed version
apt-cache policy visual-studio-2022 || rpm -q visual-studio-2022 || visual-studio-2022 --version
2. UPGRADE to 17.14.40 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade visual-studio-2022
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade visual-studio-2022
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 17.14.0 (Debian / Ubuntu)
apt-cache madison visual-studio-2022
sudo apt install visual-studio-2022=<VERSION_BEFORE_17.14.0>
sudo apt-mark hold visual-studio-2022
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list visual-studio-2022
sudo dnf downgrade visual-studio-2022-<VERSION_BEFORE_17.14.0>
sudo dnf versionlock add visual-studio-2022
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
microsoft visual studio 2026 UPGRADE
Affected: >= 18.9.0 and < 18.9.3
Fixed in: 18.9.3
Safe to downgrade to: a release before 18.9.0
1. Check installed version
apt-cache policy visual-studio-2026 || rpm -q visual-studio-2026 || visual-studio-2026 --version
2. UPGRADE to 18.9.3 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade visual-studio-2026
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade visual-studio-2026
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 18.9.0 (Debian / Ubuntu)
apt-cache madison visual-studio-2026
sudo apt install visual-studio-2026=<VERSION_BEFORE_18.9.0>
sudo apt-mark hold visual-studio-2026
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list visual-studio-2026
sudo dnf downgrade visual-studio-2026-<VERSION_BEFORE_18.9.0>
sudo dnf versionlock add visual-studio-2026
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
microsoft .net UPGRADE
Affected: >= 8.0.0 and < 8.0.31 · >= 9.0.0 and < 9.0.20 · >= 10.0.0 and < 10.0.12
Fixed in: 8.0.31, 9.0.20, 10.0.12
Safe to downgrade to: a release before 8.0.0
1. Check installed version
apt-cache policy .net || rpm -q .net || .net --version
2. UPGRADE to 8.0.31 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade .net
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade .net
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 8.0.0 (Debian / Ubuntu)
apt-cache madison .net
sudo apt install .net=<VERSION_BEFORE_8.0.0>
sudo apt-mark hold .net
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list .net
sudo dnf downgrade .net-<VERSION_BEFORE_8.0.0>
sudo dnf versionlock add .net
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-69304?
asp.net core: upgrade to 8.0.28, 9.0.17, 10.0.9; visual studio 2022: upgrade to 17.14.40; visual studio 2026: upgrade to 18.9.3. Exact commands for each OS are on this page.
Is CVE-2026-69304 being exploited?
CVE-2026-69304 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-69304 affect?
CVE-2026-69304 affects asp.net core, visual studio 2022, visual studio 2026. Severity is medium (CVSS 5.9). Improper handling of highly compressed data (data amplification) in ASP.NET Core allows an unauthorized attacker to deny service over a network.
How urgent is CVE-2026-69304?
Priority 45/100. Remotely exploitable, no login, no user action; On your watchlist
Software pages
.NET vulnerabilities · Visual Studio vulnerabilities
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