Versions of Express.js prior to 4.19.2 and pre-release alpha and beta versions before 5.0.0-beta.3 are affected by an open redirect vulnerability using malformed URLs.
When a user of Express performs a redirect using a user-provided URL Express performs an encode using encodeurl on the contents before passing it to the location header. This can cause malformed URLs to be evaluated in unexpected ways by common redirect allow list implementations in Express applications, leading to an Open Redirect via bypass of a properly implemented allow list.
The main method impacted is res.location() but this is also called from within res.redirect().
An initial fix went out with express@4.19.0, we then patched a feature regression in 4.19.1 and added improved handling for the bypass in 4.19.2.
Workarounds
The fix for this involves pre-parsing the url string with either require('node:url').parse or new URL. These are steps you can take on your own before passing the user input string to res.location or res.redirect.
In express <4.20.0, passing untrusted user input - even after sanitizing it - to response.redirect() may execute untrusted code
Patches
this issue is patched in express 4.20.0
Workarounds
users are encouraged to upgrade to the patched version of express, but otherwise can workaround this issue by making sure any untrusted inputs are safe, ideally by validating them against an explicit allowlist
Details
successful exploitation of this vector requires the following:
The attacker MUST control the input to response.redirect()
express MUST NOT redirect before the template appears
the browser MUST NOT complete redirection before:
the user MUST click on the link in the template
Release Notes
expressjs/express (express)
### [`v4.20.0`](https://redirect.github.com/expressjs/express/blob/HEAD/History.md#4200--2024-09-10)
[Compare Source](https://redirect.github.com/expressjs/express/compare/4.19.2...4.20.0)
\==========
- deps: serve-static@0.16.0
- Remove link renderization in html while redirecting
- deps: send@0.19.0
- Remove link renderization in html while redirecting
- deps: body-parser@0.6.0
- add `depth` option to customize the depth level in the parser
- IMPORTANT: The default `depth` level for parsing URL-encoded data is now `32` (previously was `Infinity`)
- Remove link renderization in html while using `res.redirect`
- deps: path-to-regexp@0.1.10
- Adds support for named matching groups in the routes using a regex
- Adds backtracking protection to parameters without regexes defined
- deps: encodeurl@~2.0.0
- Removes encoding of `\`, `|`, and `^` to align better with URL spec
- Deprecate passing `options.maxAge` and `options.expires` to `res.clearCookie`
- Will be ignored in v5, clearCookie will set a cookie with an expires in the past to instruct clients to delete the cookie
Configuration
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This PR contains the following updates:
4.19.2->4.20.0GitHub Vulnerability Alerts
CVE-2024-29041
Impact
Versions of Express.js prior to 4.19.2 and pre-release alpha and beta versions before 5.0.0-beta.3 are affected by an open redirect vulnerability using malformed URLs.
When a user of Express performs a redirect using a user-provided URL Express performs an encode using
encodeurlon the contents before passing it to thelocationheader. This can cause malformed URLs to be evaluated in unexpected ways by common redirect allow list implementations in Express applications, leading to an Open Redirect via bypass of a properly implemented allow list.The main method impacted is
res.location()but this is also called from withinres.redirect().Patches
https://github.com/expressjs/express/commit/0867302ddbde0e9463d0564fea5861feb708c2dd https://github.com/expressjs/express/commit/0b746953c4bd8e377123527db11f9cd866e39f94
An initial fix went out with
express@4.19.0, we then patched a feature regression in4.19.1and added improved handling for the bypass in4.19.2.Workarounds
The fix for this involves pre-parsing the url string with either
require('node:url').parseornew URL. These are steps you can take on your own before passing the user input string tores.locationorres.redirect.References
https://github.com/expressjs/express/pull/5539 https://github.com/koajs/koa/issues/1800 https://expressjs.com/en/4x/api.html#res.location
CVE-2024-43796
Impact
In express <4.20.0, passing untrusted user input - even after sanitizing it - to
response.redirect()may execute untrusted codePatches
this issue is patched in express 4.20.0
Workarounds
users are encouraged to upgrade to the patched version of express, but otherwise can workaround this issue by making sure any untrusted inputs are safe, ideally by validating them against an explicit allowlist
Details
successful exploitation of this vector requires the following:
Release Notes
expressjs/express (express)
### [`v4.20.0`](https://redirect.github.com/expressjs/express/blob/HEAD/History.md#4200--2024-09-10) [Compare Source](https://redirect.github.com/expressjs/express/compare/4.19.2...4.20.0) \========== - deps: serve-static@0.16.0 - Remove link renderization in html while redirecting - deps: send@0.19.0 - Remove link renderization in html while redirecting - deps: body-parser@0.6.0 - add `depth` option to customize the depth level in the parser - IMPORTANT: The default `depth` level for parsing URL-encoded data is now `32` (previously was `Infinity`) - Remove link renderization in html while using `res.redirect` - deps: path-to-regexp@0.1.10 - Adds support for named matching groups in the routes using a regex - Adds backtracking protection to parameters without regexes defined - deps: encodeurl@~2.0.0 - Removes encoding of `\`, `|`, and `^` to align better with URL spec - Deprecate passing `options.maxAge` and `options.expires` to `res.clearCookie` - Will be ignored in v5, clearCookie will set a cookie with an expires in the past to instruct clients to delete the cookieConfiguration
📅 Schedule: Branch creation - "" (UTC), Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
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