CVE-2026-50268: Steeltoe Steeltoe.Configuration.Encryption cryptographic downgrade to PKCS#1 v1.5

CVE-2026-50268 · Severity: low · CVSS 3.1 · Published 2026-06-17

Steeltoe, a library for building cloud-native applications, contains a flaw where it fails to use the requested high-security encryption (OAEP) for configuration data. Instead, it silently falls back to an older, less secure method (PKCS#1 v1.5). While there is currently no known way for an attacker to exploit this in standard setups, it leaves the system vulnerable to advanced cryptographic attacks if the decryption process is ever exposed to unauthorized users.

Vendors: NuGet, SteeltoeOSS.

Quick answers

Is CVE-2026-50268 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-50268 being exploited in the wild.
How severe is CVE-2026-50268?
Low severity, with a CVSS score of 3.1, published 17 June 2026.
Which products and versions are affected?
Steeltoe.Configuration.Encryption (NuGet) ECOSYSTEM:introduced=4.0.0,fixed=4.2.0; SteeltoeOSS Configuration.Encryption >= 4.0.0, <= 4.1.0; SteeltoeOSS Steeltoe.Configuration.Encryption >= 4.0.0, < 4.2.0.
Is there a fix for CVE-2026-50268?
Yes. Steeltoe.Configuration.Encryption (NuGet): upgrade to 4.2.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-50268 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-50268?
Check whether you run Steeltoe.Configuration.Encryption (NuGet), SteeltoeOSS Configuration.Encryption or SteeltoeOSS Steeltoe.Configuration.Encryption at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Steeltoe.Configuration.Encryption (NuGet): upgrade to 4.2.0 or later
    dotnet add package Steeltoe.Configuration.Encryption --version 4.2.0

Technical details

A vulnerability exists in Steeltoe.Configuration.Encryption (versions 4.0.0 to 4.1.0) where configuring 'encrypt:rsa:algorithm=OAEP' fails to enable OAEP padding. Due to an incorrect BouncyCastle transformation string, the library silently defaults to PKCS#1 v1.5. While currently mitigated by the fact that decryption is typically performed only on operator-controlled data, this flaw creates a potential Bleichenbacher side-channel vulnerability if a decryption oracle were to be exposed. The issue is resolved in version 4.2.0, though users must re-encrypt existing ciphertexts as the fix changes the required padding for decryption.

Affected products

  • SteeltoeOSS Steeltoe.Configuration.Encryption >= 4.0.0, <= 4.1.0

Identifiers

  • CVE-2026-50268
  • GHSA-4j9m-h44m-2hv8

Timeline

  • 2026-05-29: disclosed: Initial disclosure by maintainers
  • 2026-06-17: advisory: NVD published date
  • 2026-07-02: patched: GitHub Advisory published/reviewed

References

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