CVE-2026-42811
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Privilege Escalation in Apache Polaris via CEL Injection

Publication date: 2026-05-04

Last updated on: 2026-05-04

Assigner: Apache Software Foundation

Description
In plain terms, Apache Polaris is supposed to issue short-lived GCS credentials that only work for one table's files, but a crafted namespace or table name can cause those credentials to work across the configured bucket instead. Apache Polaris builds Google Cloud Storage downscoped credentials by creating a Credential Access Boundary (CAB) with CEL conditions that are intended to restrict access to the requested table's storage path. The relevant CEL string is built from the bucket name and the table path. That table path is derived from namespace and table identifiers. In current code, that path appears to be inserted into the CEL expression without escaping. As a result, a namespace or table identifier containing a single quote and other URI-safe CEL fragments can break out of the intended quoted string and change the meaning of the CEL condition. In private testing against Polaris 1.4.0 on real Google Cloud Storage, it was confirmed that Polaris accepted a crafted identifier and returned delegated GCS credentials whose CEL path restriction had effectively collapsed. Those delegated credentials could then: - list another table's object prefix; - read another table's metadata control file (Iceberg metadata JSON); - create and delete an object under another table's object prefix; - and also list, read, create, and delete objects under an unrelated external prefix in the same bucket that was not part of any table path. That last point is important. The issue is not limited to "another table". In the confirmed setup, once Apache Polaris returned credentials for the crafted table, the path restriction inside the configured bucket was effectively gone. The practical effect is that temporary credentials for one crafted table can be broader than the table Polaris was asked to authorize, and can become effectively bucket-wide within the configured bucket. The current GCS testing used a Polaris principal with broad catalog privileges for setup. A separate least-privilege Polaris RBAC variant has not yet been tested on GCS. However, the storage-credential broadening behavior itself has been confirmed on GCS.
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Meta Information
Published
2026-05-04
Last Modified
2026-05-04
Generated
2026-05-07
AI Q&A
2026-05-05
EPSS Evaluated
2026-05-05
NVD
CVE-2026-42811
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
apache polaris 1.4.0
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-917 The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.
CWE-20 The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

Apache Polaris is designed to issue short-lived Google Cloud Storage (GCS) credentials that restrict access to files belonging to a single table. However, due to improper handling of namespace or table names, specifically when these contain special characters like single quotes, the credentials can be crafted to bypass these restrictions.

This happens because the table path, derived from namespace and table identifiers, is inserted into a Credential Access Boundary (CAB) expression without proper escaping. This allows an attacker to manipulate the CEL (Common Expression Language) condition that restricts access, effectively broadening the scope of the credentials.

As a result, credentials intended for one table can be used to access the entire configured bucket, allowing unauthorized listing, reading, creating, and deleting of objects across multiple tables and unrelated prefixes within the bucket.


How can this vulnerability impact me? :

This vulnerability can lead to unauthorized access and modification of data within a Google Cloud Storage bucket. Specifically, an attacker with crafted namespace or table names can obtain credentials that allow them to:

  • List objects belonging to other tables.
  • Read metadata control files of other tables.
  • Create and delete objects under other tables' prefixes.
  • Access, create, and delete objects under unrelated external prefixes within the same bucket.

This broad access can lead to data leakage, unauthorized data manipulation, and potential disruption of services relying on the integrity and confidentiality of the stored data.


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