Critical [CVE-2026-55976] Server-Side Request Forgery (SSRF) in Avro SerDe schema resolution in Apache Hive before 4.2.1 allows an authenticated remote attacker with CREATE TABLE privilege to cause the Hive server to fetch an attacker-controlled URL when resolving the avro.schema.url table property on an Avro table that is subsequently queried

Server-Side Request Forgery (SSRF) in Avro SerDe schema resolution in Apache Hive before 4.2.1 allows an authenticated remote attacker with CREATE TABLE privilege to cause the Hive server to fetch an attacker-controlled URL when resolving the avro.schema.url table property on an Avro table that is subsequently queried.

This can expose cloud instance metadata, internal network services, or local server files to the Hive process identity. Users are recommended to upgrade to version 4.2.1, which fixes this issue.

Attacker access requirements:

• Network access to HiveServer2 / Metastore: required (remote attacker model).
• Valid Hive authentication: required.
• CREATE TABLE (or equivalent) privilege: required, so the attacker can set avro.schema.url in table properties.
• SELECT privilege on the malicious table: not required for the creator, who can typically query their own table; any other user granted SELECT can also trigger the fetch.
• Write access to the table LOCATION: not required; the attack uses the schema URL, not the data path.
• Admin / superuser privileges: not required; an ordinary authenticated user with DDL rights is sufficient.
• External tables enabled: typically required in practice, and enabled by default in most deployments.

Detection guidance: