Skip to content

fix(function): validate custom tool param keys before code interpolation #4474

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
waleedlatif1 merged 2 commits into from
May 6, 2026
+61 −2
Merged

fix(function): validate custom tool param keys before code interpolation #4474

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
602339c
fix(function): validate custom tool param keys before code interpolation
waleedlatif1 May 6, 2026
507ccba
fix(function): exclude JS reserved words from param key injection guard
waleedlatif1 May 6, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
63 changes: 61 additions & 2 deletions apps/sim/app/api/function/execute/route.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,59 @@ const TAG_PATTERN = createReferencePattern()
const E2B_JS_WRAPPER_LINES = 3
const E2B_PYTHON_WRAPPER_LINES = 1

/** Matches valid JS identifier names (letters, digits, underscore; no leading digit). */
const SAFE_IDENTIFIER = /^[a-zA-Z_][a-zA-Z0-9_]*$/

/** ES2023 reserved words — using these as `const` variable names produces a SyntaxError. */
const JS_RESERVED_WORDS = new Set([
'break',
'case',
'catch',
'class',
'const',
'continue',
'debugger',
'default',
'delete',
'do',
'else',
'export',
'extends',
'false',
'finally',
'for',
'function',
'if',
'import',
'in',
'instanceof',
'let',
'new',
'null',
'return',
'static',
'super',
'switch',
'this',
'throw',
'true',
'try',
'typeof',
'var',
'void',
'while',
'with',
'yield',
'enum',
'await',
'implements',
'interface',
'package',
'private',
'protected',
'public',
])

type TypeScriptModule = typeof import('typescript')

let typescriptModulePromise: Promise<TypeScriptModule> | null = null
Expand Down Expand Up @@ -1089,18 +1142,24 @@ export const POST = withRouteHandler(async (req: NextRequest) => {

const executionMethod = 'isolated-vm'

const isSafeParamKey = (key: string) => SAFE_IDENTIFIER.test(key) && !JS_RESERVED_WORDS.has(key)

const wrapperLines = ['(async () => {', ' try {']
if (isCustomTool) {
Object.keys(executionParams).forEach((key) => {
wrapperLines.push(` const ${key} = params.${key};`)
if (isSafeParamKey(key)) {
wrapperLines.push(` const ${key} = params.${key};`)
} else {
logger.warn('Skipping param key — not a safe JS identifier', { key, requestId })
}
})
}
userCodeStartLine = wrapperLines.length + 1

let codeToExecute = resolvedCode
let prependedLineCount = 0
if (isCustomTool) {
const paramKeys = Object.keys(executionParams)
const paramKeys = Object.keys(executionParams).filter(isSafeParamKey)
const paramDestructuring = paramKeys.map((key) => `const ${key} = params.${key};`).join('\n')
codeToExecute = `${paramDestructuring}\n${resolvedCode}`
prependedLineCount = paramKeys.length
Expand Down
Loading