Medium [CVE-2026-72656] Denial of Service via excessive memory allocation in ES|QL queries
This medium-severity Red Hat Linux advisory covers CVE-2026-72656.
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Summary
Memory Allocation with Excessive Size Value (CWE-789) in the ES|QL query processing of Elasticsearch can lead to denial of service via Excessive Allocation (CAPEC-130).
An authenticated user able to submit ES|QL queries could send a specially crafted query whose evaluation allocates an unbounded amount of heap memory, exhausting the available heap on the receiving node and causing the node to become unavailable. A flaw was found in Elasticsearch.
This excessive memory consumption exhausts the available resources on the receiving node, leading to a denial of service (DoS) condition where the node becomes unavailable. When evaluating a specially crafted ES|QL query, the engine fails to enforce upper bounds on memory allocation requests, triggering unbounded heap consumption.
An authenticated remote attacker can exploit this issue by submitting malformed queries to exhaust the receiving node's heap memory, causing node instability or service crashes, posing an Important impact to availability. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-789.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 23 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 23 days ago·verify at source
Mitigation checklist
- Restrict ES|QL query permissions using Elasticsearch role-based access control (RBAC) so that only trusted users can submit queries. Additionally, configure request circuit breakers (`indices.breaker.request.limit`) to restrict maximum memory usage per query execution.
Official advisory · high-confidence parse· fetched 23 days ago·verify at source
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