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fix(isBase64): simplify padding RegExp to prevent stack overflow #2574

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Merged
merged 2 commits into from
Aug 27, 2025
Merged

fix(isBase64): simplify padding RegExp to prevent stack overflow #2574

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e947d6f
#2491 #2573 Simplify isBase64 to prevent stack overflow
Jul 14, 2025
12211ff
Merge branch 'master' into master
rubiin Aug 27, 2025
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6 changes: 4 additions & 2 deletions src/lib/isBase64.js
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Original file line number Diff line number Diff line change
@@ -1,9 +1,9 @@
import assertString from './util/assertString';
import merge from './util/merge';

const base64WithPadding = /^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/;
const base64WithPadding = /^[A-Za-z0-9+/]+={0,2}$/;
const base64WithoutPadding = /^[A-Za-z0-9+/]+$/;
const base64UrlWithPadding = /^(?:[A-Za-z0-9_-]{4})*(?:[A-Za-z0-9_-]{2}==|[A-Za-z0-9_-]{3}=|[A-Za-z0-9_-]{4})$/;
const base64UrlWithPadding = /^[A-Za-z0-9_-]+={0,2}$/;
const base64UrlWithoutPadding = /^[A-Za-z0-9_-]+$/;

export default function isBase64(str, options) {
Expand All @@ -12,6 +12,8 @@ export default function isBase64(str, options) {

if (str === '') return true;

if (options.padding && str.length % 4 !== 0) return false;

let regex;
if (options.urlSafe) {
regex = options.padding ? base64UrlWithPadding : base64UrlWithoutPadding;
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