CVE-2026-64640

CVE-2026-64640 is a validation-ordering vulnerability in Polaris that allows unauthorized S3 object reads. The core issue: Polaris vends S3 credentials and then reads Iceberg metadata files from caller-specified paths—but it performs the allowed-locations check only after the read completes. An attacker who can request metadata file paths and who possesses valid catalog credentials can trick Polaris into reading objects outside the catalog's authorized boundaries using the catalog's own credentials. This is not merely an implementation bug. It is a structural flaw in the credential-vending pattern: the code that handles catalog logic and the code that handles credential scope execute in separate paths at different times, and no explicit contract enforces the moment where they must intersect. The dual-condition nature of this advisory—where Polaris accepts registration metadata containing external references but does not currently follow them—reveals inconsistent security contracts around location validation. These are likely separate issues requiring distinct remediation. The severity depends entirely on credential scope. If vended credentials can reach an entire S3 bucket, exposure is severe. If scoped to a narrow prefix, practical impact is minimal. You must audit what the catalog's storage credentials can actually reach, not what the catalog's allowed-locations configuration claims. The CVSS 6.5 rating reflects demonstrated impact and typical deployment constraints—it does not reflect the upper bound of potential impact. The advisory states impact is limited to confidentiality. Treat this as a scope constraint on proof-of-concept work, not a technical bound. Crafted metadata files could trigger parser side effects, memory exhaustion through oversized files, or downstream validation failures. Absence of demonstration is not proof of absence. Prioritize: first, verify your credential scope configuration and reduce it to the minimum required. Second, apply the patch that reorders validation before the read. Third, audit registration logic for similar validation-ordering patterns—the same architectural failure that caused condition one may exist elsewhere in code paths that touch vended credentials.

Reviewed through automated stages and approved by a human before publication.