Steeltoe: OAEP setting silently selects PKCS#1 v1.5 padding
Summary
Configuring encrypt:rsa:algorithm=OAEP does not enable OAEP encryption. Due to an incorrect BouncyCastle transformation string, the OAEP setting selects PKCS#1 v1.5, which is the same algorithm as the DEFAULT setting.
Impact
Operators who configure encrypt:rsa:algorithm=OAEP to obtain CCA2-secure padding receive PKCS#1 v1.5 instead. Currently, Decrypt() is called only against operator-controlled configuration data, so no exploitable path exists, but any future code path that exposes a decryption oracle would be Bleichenbacher-vulnerable despite the OAEP setting.
Migration note
Existing {cipher} values produced under the broken OAEP setting were encrypted with PKCS#1 v1.5. The fix makes OAEP use actual OAEP padding, so those values will fail to decrypt after upgrading. Re-encrypt all affected {cipher} values after upgrading.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | Steeltoe.Configuration.Encryption | >= 4.0.0, < 4.2.0 | 4.2.0 |
References
- CVSS vector
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N- Weakness (CWE)
CWE-256, CWE-327- Platform
- .NET (NuGet)
- Package
Steeltoe.Configuration.Encryption- Disclosed
- 02.07.2026
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-4j9m-h44m-2hv8 - CC BY 4.0
Vulnerability history: Steeltoe.Configuration.Encryption
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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