GHSA-ghhp-997w-qr28
CRITICALGHSA-ghhp-997w-qr28 is a critical-severity (CVSS 9.8) remote code execution vulnerability in System.Text.Encodings.Web. O3 Security confirms whether GHSA-ghhp-997w-qr28 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
.NET Core Remote Code Execution Vulnerability
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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 GHSA-ghhp-997w-qr28.
Real-World Exposure
System.Text.Encodings.Web.NETSystem.Text.Encodings.Web.NETSystem.Text.Encodings.WebReal-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
.NET Core Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-24112.
Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 5.0, .NET Core 3.1, and .NET Core 2.1. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
A remote code execution vulnerability exists in .NET 5 and .NET Core due to how text encoding is performed.
Discussion
Discussion for this issue can be found at dotnet/runtime#49377
Mitigation factors
Microsoft has not identified any mitigating factors for this vulnerability.
Affected software
The vulnerable package is System.Text.Encodings.Web . Upgrading your package and redeploying your app should be sufficient to address this vulnerability.
Vulnerable package versions:
Any .NET 5, .NET Core, or .NET Framework based application that uses the System.Text.Encodings.Web package with a vulnerable version listed below.
| Package Name | Vulnerable Versions | Secure Versions |
|---|---|---|
| System.Text.Encodings.Web | 4.0.0 - 4.5.0 | 4.5.1 |
| System.Text.Encodings.Web | 4.6.0-4.7.1 | 4.7.2 |
| System.Text.Encodings.Web | 5.0.0 | 5.0.1 |
Please validate that each of the .NET versions you are using is in support. Security updates are only provided for supported .NET versions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | System.Text.Encodings.Web | ≥ 4.0.0&&< 4.5.1 | 4.5.1 |
| .NETNuGet | System.Text.Encodings.Web | ≥ 4.6.0&&< 4.7.2 | 4.7.2 |
| .NETNuGet | System.Text.Encodings.Web | ≥ 5.0.0&&< 5.0.1 | 5.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for System.Text.Encodings.Web. 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 System.Text.Encodings.Web to 4.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ghhp-997w-qr28 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 GHSA-ghhp-997w-qr28 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 GHSA-ghhp-997w-qr28. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is GHSA-ghhp-997w-qr28 in your dependencies?
O3 detects GHSA-ghhp-997w-qr28 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.