Regular Expression Denial of Service in System.Text.RegularExpressionsGHSA-cmhx-cq75-c4mj
HIGHGHSA-cmhx-cq75-c4mj is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in System.Text.RegularExpressions. A fix is available for System.Text.RegularExpressions — see the affected versions and patch details below.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-cmhx-cq75-c4mj by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
System.Text.RegularExpressionsReal-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
A denial of service vulnerability exists when .NET Framework and .NET Core improperly process RegEx strings, aka '.NET Framework and .NET Core Denial of Service Vulnerability'. This CVE ID is unique from CVE-2019-0980, CVE-2019-0981.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | System.Text.RegularExpressions | ≥ 4.3.0&&< 4.3.1 | 4.3.1dotnet add package System.Text.RegularExpressions --version 4.3.1 |
Affected Products
.net coremicrosoft.net frameworkmicrosoftenterprise linuxredhatenterprise linux eusredhatenterprise linux server ausredhatenterprise linux server tusredhatDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for System.Text.RegularExpressions, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update System.Text.RegularExpressions to 4.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cmhx-cq75-c4mj is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is GHSA-cmhx-cq75-c4mj in your dependencies?
Find it across NuGet, including transitive dependencies.