CVE-2026-115290
Description
A flaw was found in Elasticsearch. An unauthenticated remote attacker with network access to a node's remote cluster server interface can send specially crafted requests containing deeply nested serialized data. Processing this data triggers excessive recursion, causing the affected node to crash and leading to a Denial of Service (DoS).
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
--- CME Mitigation Guidance (2026-11-04) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to enforce recursion depth limits and reject deeply nested serialized payloads received over the remote cluster server interface: upgrade to Elasticsearch 8.19.24, 9.4.9, or 9.5.6 (or the fixed Python Elasticsearch builds), which restrict recursion depth and reject deeply nested serialized payloads received over the remote cluster server interface, closing deeply nested serialized payloads. Until patched, this is a concern on Elasticsearch nodes with the remote cluster server interface enabled, so disable the remote cluster server interface or restrict network access to the interface using IP filtering. These controls limit blast radius and contain exploitation, but they do not fix the underlying uncontrolled recursion defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-1316 Algorithmic Complexity Safeguards (Pattern/Regex Execution Limits) (high)
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
Frequently Asked Questions
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