CVE-2026-21729
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Memory Exhaustion in Grafana Loki Queries

Vulnerability report for CVE-2026-21729, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-07-16

Last updated on: 2026-07-16

Assigner: Grafana Labs

Description

Loki queries with large limits can cause large memory allocations which can impact the availability of the service, depending on its deployment strategy.

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Meta Information

Published
2026-07-16
Last Modified
2026-07-16
Generated
2026-08-05
AI Q&A
2026-07-16
EPSS Evaluated
2026-08-04
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
grafana loki From 3.7.0 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

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Executive Summary

This vulnerability involves Loki queries that request large data limits. These queries can cause significant memory allocation, potentially overwhelming the service and affecting its availability depending on how it is deployed.

Detection Guidance

This vulnerability involves excessive memory allocation due to large query limits in Loki. To detect it, monitor system memory usage during query execution. Check Loki logs for large query limits or out-of-memory errors. Use commands like 'top', 'htop', or 'ps aux' to observe memory consumption by Loki processes. Look for sustained high memory usage correlating with query activity.

Impact Analysis

If you use Loki for log queries, an attacker could exploit this by sending queries with large limits, causing high memory consumption. This may slow down or crash your Loki instance, disrupting log retrieval and monitoring.

Compliance Impact

This vulnerability primarily impacts service availability due to excessive memory allocation during Loki queries with large limits. It does not directly affect data confidentiality or integrity, which are key focus areas for GDPR and HIPAA. However, prolonged service unavailability could indirectly impact compliance by disrupting access to required data or logging systems.

Mitigation Strategies

Limit the maximum query limit in Loki configuration to prevent large memory allocations. Monitor memory usage during queries and set alerts for abnormal spikes. Ensure Grafana and Loki deployments have sufficient resources to handle peak loads.

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