Improper Input Validation in Apache Parquet leaks KMS tokens via file-controlled KMS URL
AI analysis
CVE-2026-73334 is an improper input validation flaw (CWE-20) in the org.apache.parquet.crypto.keytools package of Apache Parquet, versions 1.12 through 1.18, which implements envelope encryption of Parquet files with data keys wrapped via a Key Management Service. The flaw is triggered when a reader does not application-control the KMS URL parameter, causing the KMS URL embedded in the Parquet file itself to be forwarded to a pluggable KmsClient implementation; if that client does not validate the destination host, the KMS token is sent to a malicious host specified by the attacker inside the file. An attacker who can supply or tamper with a Parquet file read under this configuration can capture the KMS token, potentially exposing key-management credentials and enabling unauthorized access to encrypted data keys — this is a credential/secret exposure issue, not remote code execution. Users of Parquet's envelope-encryption feature who rely on file-controlled KMS URLs with custom KmsClient plugins lacking host validation are affected; readers that set the KMS URL via application control are not exposed. The issue has not yet received a CVSS score, is not in CISA KEV, has no known public proof-of-concept, and there is no known exploitation in the wild; a fix is expected in version 1.19, which will disable file-controlled KMS URLs by default.
What to do: Until the fixed release (1.19, where file-controlled KMS URL is disabled by default) is available, configure readers to set the KMS URL via application control rather than trusting the URL embedded in untrusted Parquet files. If file-controlled KMS URLs must be used, ensure your custom KmsClient implementation validates the target host and uses authentication, and only process Parquet files from trusted sources. Once version 1.19 is released, upgrade and only re-enable file-controlled KMS URLs via the new application parameter if host validation and authentication are implemented in your KMS client plugin.
Affected
| Apache Parquet (Hadoop) — org.apache.parquet.crypto.keytools | 1.12 to 1.18 (fix expected in 1.19 per the disclosure) |
Estimated exposure
largelikely tens of thousands of data-platform deployments run Parquet 1.12–1.18, though only the subset enabling KMS envelope encryption with file-controlled KMS… — Parquet is a default file format bundled with Apache Spark, Hive, and most Hadoop-ecosystem engines, giving it a massive install base, but the encryption/keytools code path is opt-in and requires a custom non-validating KmsClient, so only…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
Potential problem for users of the org.apache.parquet.crypto.keytools package in Apache Parquet, versions 1.12 to 1.18. This package enables users to encrypt Parquet files via an envelope encryption mechanism that wraps (encrypts) data keys via a Key Management Service (KMS). On the reader side, the KMS URL can be application-controlled or file-controlled. If the user does not leverage application control for this parameter, a file-controlled KMS URL is forwarded to a pluggable KmsClient implementation. If the pluggable implementation does not perform host validation, a KMS token can be sent to a malicious host set by an attacker in the file. Before the problem is fixed, users are recommended to leverage application control for KMS URL parameter in readers (versions 1.12-1.18). After the problem is fixed (presumably in version 1.19), the upgrade will disable file-controlled KMS URL by default. Users of the KMS URL parameter will have two options then: leverage application control for KMS URL parameter in readers, or enable file-controlled KMS URL (via a new app parameter). The latter option will explicitly require (in the new parameter documentation) to validate the KMS URL and use authentication in the custom implementation of the KMS client plug in.