CVE-2026-56207 in Impala
Summary
by MITRE • 09/09/2026
Signature of Bearer token is not verified in last step of SAML2 authentication for Impala's hs2-http interface, allowing altering user name and acting as another user.
This issue affects Apache Impala: >=4.0.0.
Users are recommended to upgrade to version 4.5.2, which fixes this issue.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified in the SAML2 authentication flow for the HiveServer2 HTTP interface of Apache Impala represents a critical failure in identity verification mechanisms. Specifically, during the final stage of the Single Sign-On process using Security Assertion Markup Language version 2.0, the system fails to validate the cryptographic signature of the Bearer token presented by the client. This omission creates a fundamental break in the chain of trust that is essential for secure authentication protocols. In standard SAML implementations, the service provider must verify that the assertion received from the identity provider has not been tampered with and originates from a trusted source. By neglecting this verification step on the Impala side, the application effectively trusts any token structure provided by an attacker without confirming its authenticity or integrity.
This technical flaw allows for severe privilege escalation through user impersonation. An adversary who intercepts or crafts a malicious SAML assertion can modify critical fields within the authentication payload, most notably the subject identifier which maps to a specific username in the Impala environment. Since the signature is not checked, the system accepts these altered assertions as valid login attempts. Consequently, an attacker can inject arbitrary usernames into the session context, effectively logging in as any user for whom they know or can guess the identity mapping. This capability bypasses all intended access controls and authentication barriers, granting unauthorized entities full administrative privileges over the data warehouse resources associated with the targeted account.
The operational impact of this vulnerability is profound, particularly in enterprise environments where Impala serves as a central component for large-scale SQL querying on Hadoop Distributed File System data. Unauthorized users gaining access to high-privilege accounts can read sensitive corporate data, exfiltrate proprietary information, or modify and delete critical datasets. Furthermore, because the flaw exists within the authentication layer itself, it undermines the integrity of audit logs which rely on accurate user identification for compliance reporting under standards such as GDPR, HIPAA, or SOX. The ability to act as another user also facilitates lateral movement if those impersonated accounts have access to other interconnected systems or services that trust Impala's identity assertions.
From a classification perspective, this vulnerability aligns with CWE-347, which describes Improper Verification of Cryptographic Signature, and falls under the MITRE ATT&CK technique T1078, specifically Valid Accounts used for unauthorized access. The lack of signature verification means that even if transport layer security like TLS is employed to encrypt the channel, it does not protect against message manipulation at the application logic level where trust decisions are made based on flawed validation routines. This highlights a common pitfall in web service implementations where developers may assume that secure channels suffice for authentication integrity without implementing robust cryptographic checks on incoming assertions.
To mitigate this risk immediately, organizations should upgrade Apache Impala to version 4.5.2 or any later release where the signature verification logic has been corrected. Until an upgrade is feasible, network-level controls such as strict firewall rules limiting access to the HiveServer2 HTTP interface to only known and trusted IP addresses can provide a layer of defense in depth. Additionally, implementing Web Application Firewalls with specific rule sets capable of detecting anomalous SAML payloads may help block exploitation attempts by identifying malformed or unsigned assertions before they reach the application logic. Regular security audits focusing on authentication flows are recommended to ensure that similar oversights do not exist elsewhere in the infrastructure.