CVE-2026-41005: Signature Bypass (CVSS 9)

Description

Cloud Foundry UAA incorrectly treated XML encryption to the Service Provider (confidentiality) as a substitute for XML signatures from the Identity Provider (authenticity) in two SAML flows: the OAuth 2.0 SAML2 bearer grant (token endpoint) and browser SSO (ACS) when wantAssertionSigned is set to false. Assertions or responses that were unsigned but contained encrypted content could still be accepted. Encryption uses the SP's public key from published metadata, therefore, any party, not only a trusted IdP, can produce ciphertext UAA can decrypt; successful decryption therefore does not prove the IdP issued the message. Affected versions: Cloud Foundry UAA (uaa_release) 2.0.0 through 78.13.0. Cloud Foundry CF Deployment all versions through 56.1.0.

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CVSS v3.1 Score

9.0

CRITICAL

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-347 CWE-347

References

Other References

https://www.cloudfoundry.org/blog/cve-2026-41005-uaa-accepts-saml-encrypted-assertions-authentication-bypass/

Frequently Asked Questions

What is CVE-2026-41005? +

Cloud Foundry UAA incorrectly treated XML encryption to the Service Provider (confidentiality) as a substitute for XML signatures from the Identity Provider (authenticity) in two SAML flows: the OAuth 2.0 SAML2 bearer grant (token endpoint) and browser SSO (ACS) when wantAssertionSigned is set to false. Assertions or responses that were unsigned but contained encrypted content could still be accepted. Encryption uses the SP's public key from published metadata, therefore, any party, not only a trusted IdP, can produce ciphertext UAA can decrypt; successful decryption therefore does not prove the IdP issued the message. Affected versions: Cloud Foundry UAA (uaa_release) 2.0.0 through 78.13.0. Cloud Foundry CF Deployment all versions through 56.1.0. It has a CVSS v3.1 base score of 9.0 (CRITICAL).

How severe is CVE-2026-41005? +

CVE-2026-41005 has a CVSS v3.1 score of 9.0 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0013, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-41005? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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