CVE-2026-50268: Steeltoe OAEP Setting Silently Selects PKCS#1 Vulnerability

LOW
Advisory Identifier: GHSA-4j9m-h44m-2hv8
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CVSS 1.9
CWE-327 CWE-256
Published
Advisory Summary

CVE-2026-50268 is a LOW (CVSS 1.9) oaep setting silently selects pkcs#1 vulnerability (CWE-327: Use of a Broken or Risky Cryptographic Algorithm) affecting Steeltoe libraries in the NuGet ecosystem. The issue involves oaep setting silently selects pkcs#1 v1.5 padding. Remediation is available by upgrading affected packages to version 4.2.0.

CVE-2026-50268 at a Glance

CVE Identifier CVE-2026-50268
GHSA Identifier GHSA-4j9m-h44m-2hv8
Severity LOW
CVSS v3.1 Base Score 1.9
CWE Classification CWE-327: Use of a Broken or Risky Cryptographic Algorithm
Affected Product Steeltoe
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 1.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Local (AV:L)
Attack Complexity High (AC:H)
Privileges Required High (PR:H)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-50268

To remediate this vulnerability, upgrade all affected Steeltoe dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Steeltoe.Configuration.Encryption fixed: 4.2.0 
Upgrade Steeltoe.Configuration.Encryption to 4.2.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for Steeltoe.Configuration.Encryption

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-50268, inspect your project dependencies for Steeltoe:

inspect dependencies for Steeltoe.Configuration.Encryption

Analyze the terminal output to locate any version of Steeltoe in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-327: Use of a Broken or Risky Cryptographic Algorithm, where the product uses a broken or risky cryptographic algorithm or protocol. In Steeltoe, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-50268 Affected Steeltoe Versions

1 component(s)
Fixed Versions:
4.2.0
Product / Package Ecosystem Affected Versions Fixed Version
Steeltoe.Configuration.Encryption
nuget/Steeltoe.Configuration.Encryption
NuGet
≥ 4.0.0
< 4.2.0
4.2.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-4j9m-h44m-2hv8
NVD — CVE-2026-50268 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-50268
Security Fix Commit FIX COMMIT
https://github.com/SteeltoeOSS/Steeltoe/commit/6cfee5cccddf8f9a31de69b0ca5ccdd771b73e5b
Steeltoe Source Repository REPOSITORY
https://github.com/SteeltoeOSS/security-advisories

Frequently Asked Questions

What is CVE-2026-50268?
CVE-2026-50268 is a security vulnerability in Steeltoe involving OAEP setting silently selects PKCS#1 v1.5 padding under CWE-327: Use of a Broken or Risky Cryptographic Algorithm.
Which Steeltoe versions are affected?
Affected versions include releases prior to 4.2.0 across affected packages: Steeltoe.Configuration.Encryption.
What version fixes CVE-2026-50268?
Upgrading to 4.2.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Steeltoe.Configuration.Encryption affected?
Yes, Steeltoe.Configuration.Encryption is affected in releases prior to 4.2.0. Upgrade your dependency to 4.2.0 or later.
What is the CVSS score of CVE-2026-50268?
CVE-2026-50268 has a CVSS v3.1 base score of 1.9 (LOW) with vector string CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-50268?
CVE-2026-50268 is classified under CWE-327: Use of a Broken or Risky Cryptographic Algorithm (The product uses a broken or risky cryptographic algorithm or protocol.).
How can I check NuGet dependencies for CVE-2026-50268?
Run the dependency tree command: 'inspect dependencies for Steeltoe.Configuration.Encryption'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4j9m-h44m-2hv8",
  "modified" : "2026-07-02T20:32:21Z",
  "published" : "2026-07-02T20:32:21Z",
  "aliases" : [ "CVE-2026-50268" ],
  "summary" : "Steeltoe: OAEP setting silently selects PKCS#1 v1.5 padding",
  "details" : "### Summary\n\nConfiguring `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.\n\n### Impact\n\nOperators 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.\n\n### Migration note\n\nExisting `{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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Configuration.Encryption"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.2.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-4j9m-h44m-2hv8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-50268"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/commit/6cfee5cccddf8f9a31de69b0ca5ccdd771b73e5b"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SteeltoeOSS/security-advisories"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-256", "CWE-327" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T20:32:21Z",
    "nvd_published_at" : "2026-06-17T23:17:04Z"
  }
}