Security Bulletin: Due to use of pac4j, IBM Cloud PAK for Watson AI Ops is vulnerable to token bypass (CVE-2021-44878)

Summary

If an OpenID Connect provider supports the “none” algorithm (i.e., tokens with no signature), pac4j v5.3.0 (and prior) does not refuse it without an explicit configuration on its side or for the “idtoken” response type which is not secure and violates the OpenID Core Specification. The “none” algorithm does not require any signature verification when validating the ID tokens, which allows the attacker to bypass the token validation by injecting a malformed ID token using “none” as the value of “alg” key in the header with an empty signature value.

Vulnerability Details

CVEID:CVE-2021-44878
**DESCRIPTION:**pac4j could allow a remote attacker to bypass security restrictions, caused by improper validation for ID Tokens with “none” algorithm. By injecting a specially-crafted ID token using “none” as the value of “alg” key, an attacker could exploit this vulnerability to bypass the token validation.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/216856 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)

Affected Products and Versions

Remediation/Fixes

Address the vulnerabilities now for all affected products/versions listed above by installing Fix:
<https://www.ibm.com/docs/en/cloud-paks/cloud-pak-watson-aiops/3.4.2?topic=upgrading&gt;

Workarounds and Mitigations

None