Add protections for loop-bound injections by christopherholland-workday · Pull Request #5773 · FlowiseAI/Flowise

christopherholland-workday · 2026-02-18T00:01:47Z

Adding checks to prevent DoS due to large loop boundaries.

gemini-code-assist · 2026-02-18T00:02:04Z

Summary of Changes

Hello @christopherholland-workday, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the application's security posture by introducing comprehensive input validation and array size limitations across several key evaluation-related functions. The changes aim to prevent Denial of Service vulnerabilities that could arise from processing unusually large or malformed data inputs, thereby improving the stability and resilience of the evaluation system.

Highlights

Denial of Service (DoS) Protections: Implemented robust input validation and size limits for various arrays and lists to prevent potential DoS attacks caused by excessively large inputs.
Evaluation Runner Enhancements: Added checks in EvaluationRunner to ensure chatflowIds and dataset.rows are valid arrays and do not exceed predefined maximum lengths (1000 each).
Evaluator Runner Input Validation: Introduced size limits for actualOutputArray (10000), selectedEvaluators (1000), and splitValues (1000) within the runAdditionalEvaluators function to safeguard against unbounded iterations.
Evaluation Creation Safeguards: Applied validation and size limits for chatflowTypes (1000), simpleEvaluators (1000), lLMEvaluators (1000), and chatflowIds (100) during the creation of evaluations.

Changelog

packages/components/evaluation/EvaluationRunner.ts
- Added array validation for chatflowIds and data.dataset.rows.
- Introduced maximum length checks for chatflowIds (1000) and data.dataset.rows (1000) to prevent DoS.
packages/server/src/services/evaluations/EvaluatorRunner.ts
- Defined constants MAX_OUTPUTS, MAX_EVALUATORS, and MAX_SPLIT_VALUES.
- Added validation to ensure actualOutputArray and selectedEvaluators are arrays and do not exceed their respective maximum lengths.
- Implemented size checks for splitValues (1000) in ContainsAny, ContainsAll, DoesNotContainAny, and DoesNotContainAll evaluation cases.
packages/server/src/services/evaluations/index.ts
- Added array validation for chatflowType, selectedSimpleEvaluators, and selectedLLMEvaluators.
- Introduced maximum length checks for chatflowTypes (1000), simpleEvaluators (1000), and lLMEvaluators (1000).
- Added array validation for chatflowId and a maximum length check (100) during evaluation creation.
- Refactored the passing of simpleEvaluators and lLMEvaluators to use pre-validated values from additionalConfig.

Activity

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Code Review

This pull request significantly enhances the application's resilience against Denial of Service (DoS) attacks by implementing robust input validation for array lengths and types. The introduction of MAX_ constants across EvaluationRunner.ts and EvaluatorRunner.ts, along with the corresponding checks, effectively limits the processing of excessively large inputs. This is a crucial step towards improving the overall security and stability of the evaluation services.

gemini-code-assist · 2026-02-18T00:04:58Z

packages/components/evaluation/EvaluationRunner.ts

@@ -88,6 +88,27 @@ export class EvaluationRunner {

    public async runEvaluations(data: ICommonObject) {
        const chatflowIds = JSON.parse(data.chatflowId)


The JSON.parse operation can throw an error if data.chatflowId is not a valid JSON string, leading to a generic parsing error. Wrapping this in a try-catch block would allow for a more specific and user-friendly error message, clearly indicating that the input format is incorrect.

Suggested change

const chatflowIds = JSON.parse(data.chatflowId)

let chatflowIds: string[];

try {

chatflowIds = JSON.parse(data.chatflowId);

} catch (e) {

throw new Error('chatflowId must be a valid JSON array string');

}

gemini-code-assist · 2026-02-18T00:04:59Z

packages/server/src/services/evaluations/EvaluatorRunner.ts

@@ -103,6 +121,11 @@ export const runAdditionalEvaluators = async (
                        case 'ContainsAny':
                            passed = false
                            splitValues = value.split(',').map((v) => v.trim().toLowerCase()) // Split, trim, and convert to lowercase


While the MAX_SPLIT_VALUES check is in place, the split and map operations are performed on the entire value string first. If value is extremely long and contains many delimiters, these operations could consume significant memory and CPU before the length check. For extreme edge cases, consider a more memory-efficient way to count or process elements, or validate the raw string length before splitting.

gemini-code-assist · 2026-02-18T00:04:59Z

packages/server/src/services/evaluations/index.ts

        row.average_metrics = JSON.stringify({})

+        // Parse and validate evaluator arrays to prevent DoS attacks
+        const chatflowTypes = body.chatflowType ? JSON.parse(body.chatflowType) : []


Similar to other JSON.parse calls, if body.chatflowType is provided but is not a valid JSON string, JSON.parse will throw an error. Implementing a try-catch block here would provide a more precise error message to the user about the expected JSON format.

Suggested change

const chatflowTypes = body.chatflowType ? JSON.parse(body.chatflowType) : []

let chatflowTypes: string[];

try {

chatflowTypes = body.chatflowType ? JSON.parse(body.chatflowType) : [];

} catch (e) {

throw new Error('chatflowType must be a valid JSON array string');

}

gemini-code-assist · 2026-02-18T00:04:59Z

packages/server/src/services/evaluations/index.ts

+            throw new Error(`Cannot evaluate more than ${MAX_CHATFLOW_TYPES} chatflow types at once`)
+        }
+
+        const simpleEvaluators = body.selectedSimpleEvaluators.length > 0 ? JSON.parse(body.selectedSimpleEvaluators) : []


To provide a clearer error message in case body.selectedSimpleEvaluators is not a valid JSON string, it's recommended to wrap the JSON.parse call in a try-catch block.

Suggested change

const simpleEvaluators = body.selectedSimpleEvaluators.length > 0 ? JSON.parse(body.selectedSimpleEvaluators) : []

let simpleEvaluators: string[];

try {

simpleEvaluators = body.selectedSimpleEvaluators.length > 0 ? JSON.parse(body.selectedSimpleEvaluators) : [];

} catch (e) {

throw new Error('selectedSimpleEvaluators must be a valid JSON array string');

}

gemini-code-assist · 2026-02-18T00:04:59Z

packages/server/src/services/evaluations/index.ts


        if (body.evaluationType === 'llm') {
-            additionalConfig.lLMEvaluators = body.selectedLLMEvaluators.length > 0 ? JSON.parse(body.selectedLLMEvaluators) : []
+            const lLMEvaluators = body.selectedLLMEvaluators.length > 0 ? JSON.parse(body.selectedLLMEvaluators) : []


For improved error handling, consider adding a try-catch block around the JSON.parse call for body.selectedLLMEvaluators. This would allow for a more specific error message if the input is not valid JSON.

let lLMEvaluators: string[]; try { lLMEvaluators = body.selectedLLMEvaluators.length > 0 ? JSON.parse(body.selectedLLMEvaluators) : []; } catch (e) { throw new Error('selectedLLMEvaluators must be a valid JSON array string'); }

gemini-code-assist · 2026-02-18T00:04:59Z

packages/server/src/services/evaluations/index.ts

@@ -123,6 +153,17 @@ const createEvaluation = async (body: ICommonObject, baseURL: string, orgId: str
        // When chatflow has an APIKey
        const apiKeys: { chatflowId: string; apiKey: string }[] = []
        const chatflowIds = JSON.parse(body.chatflowId)


Similar to other JSON.parse operations, if body.chatflowId is not a valid JSON string, a generic parsing error will occur. A try-catch block would enable a more informative error message for invalid JSON input.

let chatflowIds: string[]; try { chatflowIds = JSON.parse(body.chatflowId); } catch (e) { throw new Error('chatflowId must be a valid JSON array string'); }

HenryHengZJ · 2026-02-24T20:09:47Z

im not a fan of hardcoding limit to prevent DoS. Since evaluateChatflow function is calling the prediction endpoint, this is essentially the same as DoS-ing /prediction endpoint. IMO, this is more on the infra level protection. Our AWS WAF should already give us some default DoS protection

christopherholland-workday · 2026-02-25T21:49:36Z

Not sure why this says it was merged, it is not in the history: https://github.com/FlowiseAI/Flowise/pulls?q=is%3Apr+is%3Aclosed

And I did not merge it

Add protections for loop-bound injections

45fc4c3

christopherholland-workday requested review from 0xi4o, HenryHengZJ, igor-magun-wd and yau-wd February 18, 2026 00:03

gemini-code-assist bot reviewed Feb 18, 2026

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igor-magun-wd approved these changes Feb 18, 2026

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christopherholland-workday merged commit 7e46279 into main Feb 25, 2026
7 checks passed

christopherholland-workday mentioned this pull request Feb 25, 2026

Revert "Add protections for loop-bound injections" #5847

Merged

christopherholland-workday mentioned this pull request Feb 25, 2026

Add protections for loop-bound injections #5849

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Add protections for loop-bound injections#5773

Add protections for loop-bound injections#5773
christopherholland-workday merged 1 commit intomainfrom
loop-bound-injection

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		@@ -88,6 +88,27 @@ export class EvaluationRunner {

		public async runEvaluations(data: ICommonObject) {
		const chatflowIds = JSON.parse(data.chatflowId)

-        const chatflowIds = JSON.parse(data.chatflowId)
+        let chatflowIds: string[];
+        try {
+            chatflowIds = JSON.parse(data.chatflowId);
+        } catch (e) {
+            throw new Error('chatflowId must be a valid JSON array string');
+        }

-        const chatflowTypes = body.chatflowType ? JSON.parse(body.chatflowType) : []
+        let chatflowTypes: string[];
+        try {
+            chatflowTypes = body.chatflowType ? JSON.parse(body.chatflowType) : [];
+        } catch (e) {
+            throw new Error('chatflowType must be a valid JSON array string');
+        }

-        const simpleEvaluators = body.selectedSimpleEvaluators.length > 0 ? JSON.parse(body.selectedSimpleEvaluators) : []
+        let simpleEvaluators: string[];
+        try {
+            simpleEvaluators = body.selectedSimpleEvaluators.length > 0 ? JSON.parse(body.selectedSimpleEvaluators) : [];
+        } catch (e) {
+            throw new Error('selectedSimpleEvaluators must be a valid JSON array string');
+        }

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