---
id: CVE-2026-50268
title: 'Steeltoe: OAEP setting silently selects PKCS#1 v1.5 padding'
summary: 'Steeltoe: OAEP setting silently selects PKCS#1 v1.5 padding'
severity: low
cvss: 1.9
cwe:
  - CWE-256
  - CWE-327
vendor: Steeltoe
product: Steeltoe.Configuration.Encryption
ecosystem: nuget
affected:
  - 'Steeltoe.Configuration.Encryption >= 4.0.0, <= 4.1.0'
patched:
  - Steeltoe.Configuration.Encryption 4.2.0
published: '2026-07-02'
updated: '2026-07-02'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-4j9m-h44m-2hv8'
references:
  - url: >-
      https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-4j9m-h44m-2hv8
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-50268'
  - url: >-
      https://github.com/SteeltoeOSS/Steeltoe/commit/6cfee5cccddf8f9a31de69b0ca5ccdd771b73e5b
  - url: 'https://github.com/advisories/GHSA-4j9m-h44m-2hv8'
tags:
  - ghsa
  - nuget
epss: 0.00059
epssPercentile: 0.00006
ingestedAt: '2026-07-02T20:42:45.622Z'
---

## Overview

### 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 packages

- `Steeltoe.Configuration.Encryption >= 4.0.0, <= 4.1.0`

## Remediation

Upgrade to a patched release:

- `Steeltoe.Configuration.Encryption 4.2.0`