OpenSearch SQL Plugin CVE-2026-83497

Exploitation requires a valid account on the target OpenSearch cluster with at minimum basic read/search permissions - no administrative or elevated role is needed. The OpenSearch SQL plugin must be installed (it ships bundled with OpenSearch by default, making this a common configuration). The attacker must be able to reach the plugins/sql endpoint over the network. No special configuration beyond the default install is required. Limiting factors include: the requirement for any authenticated account (PR:L - unauthenticated exploitation is not possible), and the need to identify a working Java gadget chain compatible with the specific classpath of the target deployment, which may require reconnaissance of the server environment. Non-default plugin removal (disabling the SQL plugin) would eliminate the attack surface.

The CVSS 4.0 score of 8.7 (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H) accurately reflects the severity: the attack is network-reachable, requires no complex setup, demands only low-privilege authentication, and yields full compromise of confidentiality, integrity, and availability on the vulnerable system. The SC:N/SI:N/SA:N metrics indicate no lateral scope change is assessed, but RCE on a search cluster typically implies access to indexed data and potential pivot points. No EPSS score was provided, limiting probabilistic exploitation forecasting. No CISA KEV listing and no publicly identified POC code were found at time of analysis, which moderates the immediate urgency slightly. However, CWE-502 Java deserialization is a well-understood and heavily tooled vulnerability class - exploitation does not require novel research once a target gadget chain is identified. Defenders should treat this as high priority for any environment where OpenSearch is cluster-internal or internet-exposed, particularly because the attacker only needs a valid account with read/search rights.

An attacker with a standard read-only OpenSearch account crafts a malicious Java serialized gadget chain - using a tool such as ysoserial with a gadget chain targeting a library present on the OpenSearch classpath - and base64-encodes it as the cursor parameter in a follow-up SQL query request to the plugins/sql endpoint. The server deserializes the parameter without class filtering, the gadget chain fires, and the attacker achieves code execution as the OpenSearch process user. No public POC has been identified, but the exploitation technique is well-established for Java deserialization vulnerabilities.