CVE-2026-82300

Executive Summary

CVE-2026-82300 is an uncontrolled resource consumption vulnerability (CWE-400) in Elasticsearch that allows an authenticated, low-privileged remote attacker to trigger excessive memory or resource allocation, resulting in denial of service. The flaw carries a CVSS v3.1 base score of 6.5 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), reflecting a network-reachable, low-complexity attack that requires only low privileges and degrades availability without impacting confidentiality or integrity. No public proof-of-concept, exploit code, or Nuclei template exists, and no patch has been identified from any tracked source, leaving affected deployments exposed unless compensating controls are applied.

Technical Analysis

CVE-2026-82300 is classified under CWE-400 (Uncontrolled Resource Consumption), mapped to CAPEC-130 (Excessive Allocation). The NVD description is sparse and does not identify the specific Elasticsearch component, API endpoint, request handler, or code path involved. Consequently, the analysis below is confined to the vulnerability class and its canonical mechanism within a search-and-analytics engine context.

CWE-400 describes a condition in which a product does not properly control the allocation and maintenance of a limited resource. In a distributed search platform such as Elasticsearch, common manifestations of this weakness class include:

• Unbounded request object allocation — a single authenticated request (or a small number of requests) causes the coordinating node to allocate memory proportional to an attacker-influenced parameter that has no enforced ceiling.
• Query or aggregation expansion — a request that induces combinatorial or multiplicative memory consumption, for example a nested or highly fan-out operation whose intermediate result set is materialized in heap before any limit is enforced.
• Lack of request-level circuit breaking — the absence or misconfiguration of heap-pressure-based rejection machinery, so that allocation continues until the Java Virtual Machine heap is exhausted.

The attack surface is the network-facing Elasticsearch REST interface, which is exposed by default on TCP port 9200 (HTTP) and 9300 (transport). The CVSS vector confirms the exposure characteristics precisely:

• AV:N — exploitable over the network, not requiring local or adjacent access.
• AC:L — no special conditions, race windows, or elevated complexity are needed.
• PR:L — the attacker must hold a valid low-privileged account. Authentication is required; this is not an anonymous DoS.
• UI:N — no user interaction on the victim side.
• S:U — impact is confined to the vulnerable Elasticsearch component's security scope.
• C:N / I:N — no confidentiality or integrity impact; no data disclosure or tampering.
• A:H — total loss of availability of the affected node or cluster.

Because the description names no specific code artefact, no function, class, parameter, or endpoint can be cited without fabrication. What is technically certain is the mechanism class: an authenticated request allocates resources without an effective bound, and the resulting exhaustion renders the service unavailable — typically by forcing the JVM into a state of continuous full garbage collection ("GC death spiral") or by triggering an OutOfMemoryError that terminates the node process. In a multi-node cluster this can cascade, as shard reallocation and cluster-state churn amplify the resource demand in the surviving nodes.

Exploitation Scenarios

No public proof-of-concept is available for CVE-2026-82300; the attack chain described below is inferred strictly from the vulnerability class (CWE-400 / CAPEC-130) and the CVSS vector. It does not rely on any fabricated endpoint, parameter, or function name.

1. Reconnaissance / target identification. The attacker identifies an internet- or intranet-exposed Elasticsearch deployment. Exposed clusters are frequently fingerprinted via their HTTP port (default 9200); a simple unauthenticated request to the cluster root returns a JSON banner containing a version.number field, which allows the operator to enumerate the release in use. The attacker enumerates reachable nodes, confirms that authentication is enforced, and obtains or already holds a low-privileged account, satisfying the PR:L condition. Where security features are disabled entirely, the attacker may already hold the equivalent of an authenticated or unrestricted role.

2. Triggering the flaw class. The attacker issues an authenticated request (or a modest set of concurrent requests) whose resource cost is not bounded by the server. Per CAPEC-130, the request induces an allocation — heap objects, result buffers, or intermediate aggregation state — that scales far beyond what any request-level limit permits. No privilege escalation, malformed payload, or memory-corruption primitive is required; the request is well-formed and passes authorization, but its resource footprint is effectively unbounded. Because AC:L applies, no race condition or timing precision is needed.

3. Execution method at the vulnerability-class level. The attacker need not inject code, deliver a file, or reach a client. The "payload" is the request itself and its allocation-inducing characteristics, transmitted directly to the Elasticsearch HTTP interface over the network. Repetition or parallelism converts a single excessive allocation into sustained exhaustion, which is the standard CAPEC-130 delivery pattern.

4. Post-exploitation impact. As heap pressure rises, the JVM spends increasing time in garbage collection, query latency degrades, and the node eventually becomes unresponsive or terminates with an OutOfMemoryError. In a clustered deployment, shard rebalancing and cluster-state updates redistribute load to remaining nodes, which can propagate the outage. Recovery may require a process restart and, in severe cases, manual shard recovery. There is no data corruption, exfiltration, or persistence associated with this vulnerability class — the impact is strictly availability, consistent with the A:H / C:N / I:N subscores.

Impact Assessment

The CVSS v3.1 base score is 6.5 (Medium), composed of an availability-only impact profile. The absence of any confidentiality or integrity subscore means the vulnerability does not directly enable data theft or modification; its entire risk is service outage. However, the business consequences of an Elasticsearch outage are frequently disproportionate to the CVSS rating:

• Search and observability blackout. Elasticsearch underpins log analytics, SIEM backends, application search, and monitoring dashboards. An outage blinds the very tooling security teams rely on for detection, creating a secondary detection gap during the incident window.
• Blast radius across the cluster. Because Elasticsearch distributes indices across nodes, exhaustion of one node can degrade or fail the entire cluster. Data ingestion pipelines (Logstash, Beats, application producers) will back up, and downstream consumers will receive stale or missing results.
• Low barrier to entry. PR:L means any holder of a low-privileged credential — an application service account, a read-only analyst, or a compromised integration key — can mount the attack. This substantially widens the pool of potential insiders and post-breach actors.
• No confirmed remediation path. With patch confidence at 0/4, there is no vendor fix to close the exposure. Mitigation must therefore be architectural and operational.

Where authentication is disabled or the cluster is directly internet-exposed, the practical risk rises substantially regardless of the PR:L designation, because the "low privilege" precondition becomes trivially satisfied.

Detection Guidance

Because no protocol-level signature, endpoint, or payload structure is published for this CVE, the rules below target the behavioural signature of excess resource consumption and anomalous cluster stress rather than a specific byte pattern. Thresholds are illustrative and must be baselined against the environment.

Sigma Rule

title: Elasticsearch Uncontrolled Resource Consumption - Node Unresponsive
id: 4a1c9e77-8230-4b1e-9c0f-2026cve8230
status: experimental
description: Detects Elasticsearch process resource exhaustion consistent with CWE-400 / CAPEC-130 denial of service
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-82300
author: valtersit.com
date: 2026/01/01
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    Image|endswith: '/java'
    CommandLine|contains: 'org.elasticsearch.bootstrap.Elasticsearch'
  condition: selection
level: informational
---
title: Elasticsearch OutOfMemoryError in Node Logs
id: 5b2d8f01-8230-4c2f-ad10-2026cve8230
status: experimental
description: Detects JVM OutOfMemoryError and sustained GC pressure in Elasticsearch logs
logsource:
  product: elasticsearch
  service: server
detection:
  keywords:
    - 'java.lang.OutOfMemoryError'
    - 'Native memory allocation (mmap) failed'
    - 'circuit_breaking_exception'
  condition: keywords
level: high

YARA Rule

rule CVE_2026_82300_Elasticsearch_Resource_Exhaustion
{
    meta:
        description = "Detects Elasticsearch log evidence of uncontrolled resource consumption (CWE-400) per CVE-2026-82300"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-82300"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $oom1 = "java.lang.OutOfMemoryError" ascii wide
        $oom2 = "GC overhead limit exceeded" ascii wide
        $oom3 = "unable to create new native thread" ascii wide
        $heap1 = "high heap usage" ascii nocase
        $heap2 = "circuit_breaking_exception" ascii nocase
        $heap3 = "Data too large" ascii nocase

    condition:
        uint32(0) != 0x504b0304 and
        (2 of ($oom*) or 2 of ($heap*))
}

Suricata IDS Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET 9200 ( \
  msg:"CVE-2026-82300 Possible Elasticsearch Resource Exhaustion DoS Attempt"; \
  flow:established,to_server; \
  content:"POST"; http_method; \
  content:"_search"; http_uri; nocase; \
  threshold:type both, track by_src, count 50, seconds 10; \
  classtype:attempted-dos; \
  reference:cve,2026-82300; \
  reference:url,www.valtersit.com; \
  sid:2026082300; rev:1; \
  metadata:service http; )

Elastic Detection

sequence by source.ip with maxspan=1m
  [ network where destination.port == 9200 and
      http.request.method == "POST" and
      http.request.body.bytes > 1000000 ]
  [ network where destination.port == 9200 and
      http.response.status_code == 429 ]

Splunk SPL Query

index=elasticsearch OR index=os sourcetype=elasticsearch:server
("OutOfMemoryError" OR "circuit_breaking_exception" OR "GC overhead limit exceeded" OR "high heap usage")
| stats count min(_time) as first_seen max(_time) as last_seen by host, source
| where count > 5
| eval first_seen=strftime(first_seen,"%Y-%m-%d %H:%M:%S"), last_seen=strftime(last_seen,"%Y-%m-%d %H:%M:%S")
| sort - count

Secondary query correlating source IPs with unusually large or high-rate search requests:

index=elasticsearch sourcetype=elasticsearch:audit
| where http_request_method="POST" AND bytes > 5000000
| stats count sum(bytes) as total_bytes by source_ip
| where count > 20
| sort - total_bytes

Wazuh OSSEC Rule

<group name="elasticsearch,cve-2026-82300,">
  <rule id="100823" level="10">
    <decoded_as>json</decoded_as>
    <match>java.lang.OutOfMemoryError</match>
    <description>CVE-2026-82300: Elasticsearch JVM out of memory - possible resource exhaustion DoS</description>
    <mitre>
      <id>T1499</id>
    </mitre>
  </rule>
  <rule id="100824" level="8">
    <decoded_as>json</decoded_as>
    <match>circuit_breaking_exception</match>
    <description>CVE-2026-82300: Elasticsearch circuit breaker triggered - memory pressure detected</description>
    <mitre>
      <id>T1499</id>
    </mitre>
  </rule>
  <rule id="100825" level="12" frequency="5" timeframe="60">
    <if_matched_sid>100824</if_matched_sid>
    <same_source_ip />
    <description>CVE-2026-82300: Repeated Elasticsearch memory pressure from single source - probable DoS attempt</description>
    <mitre>
      <id>T1499</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 0/4 (UNPATCHED). No vendor fix, workaround, or affected-version range is available from any tracked source. The following measures are class-appropriate compensating controls and do not constitute a vendor-remediated fix.

1. Immediate mitigations

• Restrict network exposure. Never expose the Elasticsearch HTTP interface (default port 9200) to untrusted networks. Place it behind a reverse proxy, API gateway, or private network segment and enforce allowlisting at the firewall and security-group layer.
• Least privilege on credentials. Because PR:L applies, any authenticated principal can trigger the condition. Audit roles and users, remove or disable unused service accounts, and constrain the privileges of integration and application accounts to the minimum dataset scope required.
• Enable and tune circuit breakers. Ensure the built-in parent, field-data, request, and in-flight-request circuit breakers are enabled and configured to reject allocations before heap exhaustion. Configure search.max_buckets-class request limits appropriate to the workload.
• Enforce rate and concurrency limits. Apply per-principal or per-source rate limiting at the proxy layer and cap concurrent expensive request classes to blunt repetition-based amplification.
• Reduce single-point failure. Limit the number of high-privilege or broadly scoped principals, and segregate cluster roles so an exhaustion event cannot cascade across all tiers.

2. Patch / upgrade steps

• Monitor the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-82300) and the Elastic security advisories page for a vendor-issued fix and an affected-version matrix.
• Until a fix is published, treat all in-scope versions as affected; do not assume a version is safe based on age or feature set.
• When a patch lands, follow the vendor's prescribed upgrade path, including rolling restart and post-upgrade verification of circuit-breaker configuration (which is sometimes reset by upgrades).

3. Long-term hardening

• Adopt heap-pressure monitoring and alerting (GC pause time, heap utilisation, 429 responses, circuit-breaker trip counts) as first-class availability SLOs.
• Maintain a formal exposure inventory: no Elasticsearch node should be reachable without an authenticated, authorised front door.
• Baseline normal request-size and request-rate distributions per principal and alert on deviations, since the CVE lacks a signature and detection must be behavioural.
• Integrate availability telemetry into the SIEM so that a resource-exhaustion event is correlated with authentication logs, identifying the principal who triggered it.

References

1. NVD — CVE-2026-82300: https://nvd.nist.gov/vuln/detail/CVE-2026-82300
2. MITRE CWE-400 — Uncontrolled Resource Consumption: https://cwe.mitre.org/data/definitions/400.html
3. MITRE CAPEC-130 — Excessive Allocation: https://capec.mitre.org/data/definitions/130.html
4. MITRE ATT&CK T1499 — Endpoint Denial of Service: https://attack.mitre.org/techniques/T1499/
5. Elastic Security Advisories (monitor for vendor fix): https://www.elastic.co/community/security

No public proof-of-concept, exploit code, Nuclei template, or CISA KEV entry is associated with this CVE. There is no confirmed exploit-in-the-wild reporting and no attributed threat actor campaign in any tracked source.