CVE-2026-42810
Published: 04 May 2026
Summary
CVE-2026-42810 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Apache Polaris. Its CVSS base score is 9.9 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 29.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-10 (Information Input Validation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Validates namespace and table name inputs to reject or sanitize literal '*' characters, preventing creation of crafted tables that generate wildcard-enabled S3 IAM policies.
Enforces approved access control policies in temporary S3 credentials by ensuring resource patterns and s3:prefix conditions properly escape wildcards, blocking cross-table access.
Remediates the specific flaw in Polaris 1.4.0 by applying vendor patches that fix unescaped '*' handling in S3 policy generation.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote exploitation of Polaris policy generation (T1190) yields unauthorized cross-table S3 access, constituting privilege escalation (T1068) that directly enables cloud storage data collection (T1530) and stored data manipulation (T1565.001).
NVD Description
Apache Polaris accepts literal `*` characters in namespace and table names. When it later builds temporary S3 access policies for delegated table access, those same characters appear to be reused unescaped in S3 IAM resource patterns and `s3:prefix` conditions. In…
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S3 IAM policy matching, `*` is treated as a wildcard rather than as ordinary text. That means temporary credentials issued for one crafted table can match the storage path of a different table. In private testing against Polaris 1.4.0 using Polaris' AWS S3 temporary- credential path on both MinIO and real AWS S3, credentials returned for crafted tables such as `f*.t1`, `f*.*`, `*.*`, and `foo.*` could reach other tables' S3 locations. The confirmed behavior includes: - reading another table's metadata control file ([Iceberg metadata JSON]); - listing another table's exact S3 table prefix ([table prefix]); - and, when write delegation was returned for the crafted table, creating and deleting an object under another table's exact S3 table prefix. A control case using ordinary different names did not allow the same cross-table access. A least-privilege AWS S3 variant was also confirmed in which the attacker principal had no Polaris permissions on the victim table and only the minimal permissions required to create and use a crafted wildcard table (namespace-scoped `TABLE_CREATE` and `TABLE_WRITE_DATA` on `*`). In that setup, direct Polaris access to `foo.t1` remained forbidden, but the attacker could still create and load `*.*`, receive delegated S3 credentials, and use those credentials to list, read, create, and delete objects under `foo.t1`. In Iceberg, the metadata JSON file is a control file: it tells readers which data files belong to the table, which snapshots exist, and which table version to read. So unauthorized access to it is already a meaningful confidentiality problem. The confirmed write-capable variant means the issue is not limited to disclosure.
Deeper analysisAI
CVE-2026-42810 affects Apache Polaris, a component that manages Iceberg tables with delegated S3 access. The vulnerability stems from Polaris accepting literal asterisk (*) characters in namespace and table names without properly escaping them when constructing temporary S3 IAM policies for delegated table access. These unescaped wildcards appear in S3 resource patterns and s3:prefix conditions, where S3 interprets * as a wildcard rather than literal text. This was confirmed in private testing against Polaris 1.4.0 using both MinIO and real AWS S3.
Attackers with low privileges (PR:L), such as namespace-scoped TABLE_CREATE and TABLE_WRITE_DATA permissions on *, can exploit this remotely (AV:N) with low complexity (AC:L) and no user interaction (UI:N). By creating crafted tables like f*.t1, f*.*, *.*, or foo.*, they obtain temporary credentials that match the S3 paths of unrelated victim tables. This enables reading another table's Iceberg metadata JSON control file (disclosing snapshots and data file locations), listing the victim's exact S3 table prefix, and, with write delegation, creating or deleting objects under the victim's prefix. Even in least-privilege scenarios without direct access to the victim table, cross-table read/write access succeeds, yielding high confidentiality, integrity, and availability impacts (C:H/I:H/A:H) with changed scope (S:C) and a CVSS v3.1 score of 9.9 (CWE-20, CWE-116).
Advisories published on Apache mailing lists (https://lists.apache.org/thread/gg3qq9sqg4hdjmprqy46p40xmln61dm9) and oss-security (http://www.openwall.com/lists/oss-security/2026/05/02/11) detail the issue, confirmed via private testing on Polaris 1.4.0. Security practitioners should review these for vendor-recommended patches or workarounds to prevent wildcard-based policy bypasses.
Details
- CWE(s)