GHSA-4j9m-h44m-2hv8
Steeltoe: OAEP setting silently selects PKCS#1 v1.5 padding
Details
### 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.
Are you affected?
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Affected packages
4.0.0 Fixed in: 4.2.0 dotnet add package Steeltoe.Configuration.Encryption --version 4.2.0 References
- https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-4j9m-h44m-2hv8 [WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-50268 [ADVISORY]
- https://github.com/SteeltoeOSS/Steeltoe/commit/6cfee5cccddf8f9a31de69b0ca5ccdd771b73e5b [WEB]
- https://github.com/SteeltoeOSS/security-advisories [PACKAGE]