CVE-2026-56207: Apache Impala: SAML authentication bypass via forged bearer token

Apache Impala's final step of SAML2 authentication on its hs2-http interface accepts a Bearer token without verifying its cryptographic signature (CWE-347). An attacker with network access to the hs2-http endpoint can submit a forged bearer token with an altered user name, and Impala will accept it as valid. This lets the attacker impersonate another user and act as that user within Impala, bypassing the SAML2 authentication control. All Apache Impala releases from version 4.0.0 onward are affected when SAML2 authentication is used with the hs2-http interface; the issue is fixed in version 4.5.2. No public proof-of-concept or in-the-wild exploitation is known, the flaw is not in CISA KEV, and CVSS has not yet been assigned.

Do: Upgrade to Apache Impala 4.5.2 as soon as practical. Until patched, restrict network access to the hs2-http interface and review hs2-http authentication/audit logs for sessions whose user name does not match corresponding IdP sign-in records to detect possible impersonation. Check whether your deployment actually uses SAML2 authentication on hs2-http, since other configurations are not affected, and watch the Apache advisory for CVSS scoring.