--- title: August 2026 Security Releases · Express.js | daily.dev description: Six vulnerabilities have been patched across three Express.js ecosystem middleware packages: hbs 4.3.0 fixes a cross-site scripting flaw in async helper... canonical: https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: August 2026 Security Releases · Express.js | daily.dev og:description: Six vulnerabilities have been patched across three Express.js ecosystem middleware packages: hbs 4.3.0 fixes a cross-site scripting flaw in async helper... og:url: https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti og:image: https://api.daily.dev/og/posts/kDzxQxLtI.png og:image:alt: August 2026 Security Releases · Express.js og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # August 2026 Security Releases · Express.js **[Express.js](https://daily.dev/sources/expressjs-blog)** · 5 min read · 2 upvotes · 0 comments ## Summary Six vulnerabilities have been patched across three Express.js ecosystem middleware packages: hbs 4.3.0 fixes a cross-site scripting flaw in async helper output, multer 2.3.0 addresses three denial-of-service issues (file descriptor leak, RangeError crash, event-loop blocking) plus a fileFilter size-limit bypass, and morgan 1.12.0 fixes log forging via unescaped Unicode line separators. Users are urged to upgrade hbs, multer, and morgan to the patched versions immediately. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What CVEs were fixed in multer 2.3.0? Multer 2.3.0 fixes four issues: CVE-2026-77037, a file descriptor leak on aborted disk-backed uploads causing resource exhaustion; CVE-2026-77078, an uncaught RangeError from crafted multipart field names that crashed the Node.js process; CVE-2026-82333, an oversized array index that blocked the event loop; and CVE-2026-77063, a fileFilter race condition allowing a file size limit bypass. _Track dependency CVEs like these multer fixes to keep upgrade decisions current on daily.dev._ ### Why does upgrading hbs to 4.3.0 matter for security? Hbs versions from 2.1.0 through 4.2.1 are vulnerable to cross-site scripting because output from helpers registered via registerAsyncHelper was not escaped the way synchronous helper output was, letting attacker-influenced data render unescaped in pages. Version 4.3.0, tracked as CVE-2026-16231 and GHSA-rg36-rxv9-2m9q, fixes this by escaping async helper output consistently with synchronous helpers. _Developers patching template-engine XSS bugs can follow fixes like this on daily.dev._ ### What is the morgan log forging vulnerability CVE-2026-15603? Morgan versions before 1.12.0 failed to escape the Unicode line separator characters U+0085, U+2028, and U+2029 in log tokens, letting an unauthenticated client inject them (for example via a Basic auth username in the remote-user token) to split one request log into multiple logical records. This follows CVE-2026-5078, which only handled ASCII control characters. Morgan 1.12.0 extends escaping to cover these Unicode characters. _Teams hardening logging middleware against injection can follow advisories like this on daily.dev._ --- Tags: [#security](https://daily.dev/tags/security), [#cyber](https://daily.dev/tags/cyber), [#nodejs](https://daily.dev/tags/nodejs), [#express](https://daily.dev/tags/express) [View this post on daily.dev](https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"August 2026 Security Releases · Express.js","url":"https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti"},"datePublished":"2026-08-31T15:44:15.139Z","dateModified":"2026-08-31T15:44:39.021Z","description":"Six vulnerabilities have been patched across three Express.js ecosystem middleware packages: hbs 4.3.0 fixes a cross-site scripting flaw in async helper...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/5eebcd3d72d39ed047cb1b9ae784c5ea?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/5eebcd3d72d39ed047cb1b9ae784c5ea?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Express.js","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Express.js","logo":"https://media.daily.dev/image/upload/s--NvBVN7aT--/f_auto,q_auto/v1787487436/logos/expressjs-blog?_a=BAMAMicg0","url":"https://daily.dev/sources/expressjs-blog"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"security,cyber,nodejs,express","timeRequired":"PT5M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Express.js","item":"https://daily.dev/sources/expressjs-blog"},{"@type":"ListItem","position":3,"name":"August 2026 Security Releases · Express.js"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/august-2026-security-releases-express-js-kdzxqxlti#faq","mainEntity":[{"@type":"Question","name":"What CVEs were fixed in multer 2.3.0?","acceptedAnswer":{"@type":"Answer","text":"Multer 2.3.0 fixes four issues: CVE-2026-77037, a file descriptor leak on aborted disk-backed uploads causing resource exhaustion; CVE-2026-77078, an uncaught RangeError from crafted multipart field names that crashed the Node.js process; CVE-2026-82333, an oversized array index that blocked the event loop; and CVE-2026-77063, a fileFilter race condition allowing a file size limit bypass. 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