CVE-2026-72687

Description

A flaw in Elasticsearch allows a low-privileged authenticated user to submit a single small request containing a forged opaque identifier. Elasticsearch decodes and deserializes the identifier before confirming that it was legitimately issued by the cluster, and a size value carried inside the identifier drives an allocation that is neither capped nor accounted for by the available memory-usage controls. The resulting out-of-memory condition is fatal and terminates the affected node process, resulting in a denial of service.

References

• https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-79/389506