7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-21728

CVE-2026-21728: Grafana Tempo has an Uncontrolled Resource Consumption issue

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

Mitigation can be done by setting max_result_limit in the search config, e.g. to 262144 (2^18).

(GitHub Advisory)

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CVE-2026-21728

CVE-2026-21728:

7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
github.com/grafana/tempo	go	>= 1.3.0, < 2.8.4	2.8.4
github.com/grafana/tempo	go	>= 2.9.0, < 2.9.2	2.9.2
github.com/grafana/tempo	go	>= 2.10.0, < 2.10.2	2.10.2

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in Grafana Tempo's search functionality, where queries with large limits could lead to excessive memory allocation and service unavailability. The root cause was an insecure default configuration that set no limit on the number of results returned by a search query (max_result_limit: 0).

The provided patch addresses this by changing the default value of max_result_limit to 262144 within the RegisterFlagsAndApplyDefaults function in modules/frontend/config.go. This function is responsible for setting up the application's configuration at startup.

While RegisterFlagsAndApplyDefaults is not the function that executes the search queries, it is the source of the insecure default that enables the vulnerability. The actual vulnerable code path is within the search query execution logic that consumes this configuration value. An attack would trigger functions within this search path, but the patch correctly identifies the configuration setup as the place for the fix. Therefore, RegisterFlagsAndApplyDefaults is a key function related to the vulnerability's mitigation.

Vulnerable functions

frontend.Config.RegisterFlagsAndApplyDefaults

modules/frontend/config.go

This function sets the default configuration for the frontend module. The patch changes the default `MaxLimit` for search queries from 0 (unlimited) to 262144. While this function itself is not the one that processes the queries, it is the place where the insecure default was set. The vulnerability is in the code that uses this configuration, which, when the limit is 0, allows for uncontrolled resource consumption.

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Miggo AI

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WAF Rule

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Reasoning

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