CVE-2026-55976 Apache Hive: SSRF vulnerability in Hive Avro Serde due to Insufficient input validation on avro.schema.url

Critical 9.1 Published 25 Aug 2026 Updated 26 Aug 2026

Authenticated attackers with table creation privileges can trigger Server-Side Request Forgery via malicious Avro schema URLs, exposing internal services and cloud metadata.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-55976?

CVE-2026-55976 is a critical server-side request forgery vulnerability in Apache Hive, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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:

* Inspect metastore / Hive table metadata for Avro tables whose avro.schema.url uses unexpected schemes such as http, https, file, or ftp, or points at link-local / cloud metadata addresses (for example 169.254.169.254) or other internal hosts. * Review HiveServer2 and Metastore logs around CREATE/ALTER TABLE and queries against Avro tables for schema-resolution failures or outbound fetches of avro.schema.url. * Correlate CREATE TABLE / ALTER TABLE activity that sets avro.schema.url with subsequent SELECT activity on the same table, especially when the URL target is unusual for schema distribution. * On cloud deployments, check instance / VPC flow logs and metadata service access logs for unexpected requests from Hive host identities shortly after Avro DDL or query activity.

Weakness: CWE-918

Which versions are affected by CVE-2026-55976?

It affects 1 product.

Products include Apache Hive.

How do I fix CVE-2026-55976?

Upgrade to a fixed version.

Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.

Is CVE-2026-55976 being exploited?

There is no known exploitation of CVE-2026-55976 in the wild and no public exploit code.

Sources

Also known as CLEANSTART-2026-BJ90324, GHSA-gp8m-92x3-q87g.