Improper Handling of Missing Special Element Affecting system.security.cryptography.cose package, versions [8.0.0-preview.1.23110.8,8.0.2)[9.0.0-preview.1.24080.9,9.0.12)[10.0.0-preview.1.25080.5,10.0.2)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DOTNET-SYSTEMSECURITYCRYPTOGRAPHYCOSE-15263815
- published11 Feb 2026
- disclosed10 Feb 2026
- creditvcsjones
Introduced: 10 Feb 2026
CVE-2026-21218 (opens in a new tab)How to fix?
Upgrade System.Security.Cryptography.Cose to version 8.0.2, 9.0.12, 10.0.2 or higher.
Overview
Affected versions of this package are vulnerable to Improper Handling of Missing Special Element in DecodeUnprotectedBucket() in CoseMessage.cs. An attacker can gain unauthorized access or manipulate data by supplying a malicious payload that bypasses security mechanisms.