fix: prototype pollution vulnerability in extend (CVE-2024-45435)

Fixes chartist-js#1427. https://nvd.nist.gov/vuln/detail/CVE-2024-45435 https://gist.github.com/tariqhawis/c67177164d3b7975210caddb25b60d62 Signed-off-by: Anders Kaseorg <[email protected]>
andersk · Oct 2, 2024 · 12b84bd · 12b84bd
1 parent 1067900
commit 12b84bd
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/src/utils/extend.ts b/src/utils/extend.ts
@@ -11,7 +11,11 @@ export function extend<T, A, B>(target: T, a: A, b: B): T & A & B;
 export function extend(target: any = {}, ...sources: any[]) {
   for (let i = 0; i < sources.length; i++) {
     const source = sources[i];
+    const targetProto = Object.getPrototypeOf(target);
     for (const prop in source) {
+      if (targetProto !== null && prop in targetProto) {
+        continue; // prevent prototype pollution
+      }
       const sourceProp = source[prop];
       if (
         typeof sourceProp === 'object' &&