.NET Framework Security Feature Bypass Vulnerability
CVE-2026-108398 · published 13 Oct 2026
How serious is it
- Severity: high, CVSS score 8.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-108398?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Microsoft Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2: 3.0.0.0 to < 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0
- Microsoft Microsoft .NET Framework 3.5 AND 4.7.2: 4.7.0 to < 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0
- Microsoft Microsoft .NET Framework 3.5 AND 4.8: 4.8.0 to < 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0
- Microsoft Microsoft .NET Framework 3.5 AND 4.8.1: 4.8.1 to < 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0
- Microsoft Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2: 4.7.0 to < 4.7.4150.0
- Microsoft Microsoft .NET Framework 4.8: 4.8.0 to < 4.8.4811.0
- Microsoft Microsoft .NET Framework 4.8.1: 4.8.0.0 to < 4.8.9363.0
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
Untrusted search path in .NET Framework allows an authorized attacker to bypass a security feature locally.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
Merged from CVE List. Last updated 27 Oct 2026. All vulnerabilities · RSS · JSON