🚨 express vulnerable to XSS via response.redirect()

Impact

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:

1. The attacker MUST control the input to response.redirect()
2. express MUST NOT redirect before the template appears
3. the browser MUST NOT complete redirection before:
4. the user MUST click on the link in the template

🚨 Express.js Open Redirect in malformed URLs

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 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().

Patches

0867302
0b74695

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.

References

#5539
koajs/koa#1800
https://expressjs.com/en/4x/api.html#res.location

Too many releases to show here. View the full release notes.

See the full diff on Github. The new version differs by more commits than we can show here.

1.3.8

• deps: mime-types@~2.1.34
  • deps: mime-db@~1.51.0
• deps: negotiator@0.6.3

1.3.7

• deps: negotiator@0.6.2
  • Fix sorting charset, encoding, and language with extra parameters

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0.5.4

• deps: safe-buffer@5.2.1

0.5.3

• Use safe-buffer for improved Buffer API

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See the full diff on Github. The new version differs by 73 commits:

• 0.5.4
• build: eslint-plugin-import@2.25.3
• build: eslint-plugin-promise@5.2.0
• tests: fix deep equal checking
• build: support Node.js 17.x
• deps: safe-buffer@5.2.1
• build: mocha@9.1.3
• build: eslint-plugin-standard@4.1.0
• build: eslint-plugin-markdown@2.2.1
• build: eslint-plugin-promise@5.1.1
• build: mocha@8.4.0
• build: support Node.js 16.x
• build: support Node.js 15.x
• build: eslint@7.32.0
• build: mocha@7.2.0
• build: support Node.js 14.x
• build: support Node.js 13.x
• build: Node.js@12.22
• build: Node.js@10.24
• lint: apply standard 13
• build: use GitHub Actions instead of Travis CI
• docs: fix typo in comment
• build: mocha@6.2.3
• build: eslint@5.16.0
• build: Node.js@10.21
• build: support Node.js 12.x
• build: support Node.js 11.x
• 0.5.3
• build: eslint-plugin-markdown@1.0.0-rc.1
• build: eslint@5.10.0
• build: Node.js@10.14
• build: Node.js@8.14
• build: Node.js@6.15
• build: mocha@5.2.0
• build: restructure Travis CI build steps
• lint: apply standard 12 style
• tests: replace deprecated assert.deepEqual with deep-equal
• build: Node.js@10.12
• build: Node.js@8.12
• tests: use strict equality
• build: support Node.js 10.x
• build: support Node.js 9.x
• build: Node.js@8.11
• deps: safe-buffer@5.1.2
• build: eslint-plugin-promise@3.8.0
• build: eslint-plugin-markdown@1.0.0-beta.8
• build: eslint-plugin-import@2.13.0
• build: Node.js@6.14
• build: Node.js@4.9
• build: use yaml eslint configuration
• docs: expand jsdoc on constructor
• lint: apply standard 11 style
• Use safe-buffer for improved Buffer API
• build: Node.js@8.9
• build: Node.js@6.12
• build: support Node.js 8.x
• build: eslint@3.19.0
• build: eslint-plugin-markdown@1.0.0-beta.6
• build: Node.js@7.10
• build: Node.js@6.11
• build: use precise dist on Travis CI
• lint: use standard style in readme
• build: eslint-config-standard@7.0.0
• build: Node.js@7.7
• build: Node.js@6.10
• build: Node.js@4.8
• build: set package author
• docs: update copyright year
• docs: use default shields badge style
• docs: update jsdoc comments
• build: eslint@3.12.2
• build: Node.js@7.4
• lint: remove unreachable branch

🚨 cookie accepts cookie name, path, and domain with out of bounds characters

Impact

The cookie name could be used to set other fields of the cookie, resulting in an unexpected cookie value. For example, serialize("userName=<script>alert('XSS3')</script>; Max-Age=2592000; a", value) would result in "userName=<script>alert('XSS3')</script>; Max-Age=2592000; a=test", setting userName cookie to <script> and ignoring value.

A similar escape can be used for path and domain, which could be abused to alter other fields of the cookie.

Patches

Upgrade to 0.7.0, which updates the validation for name, path, and domain.

Workarounds

Avoid passing untrusted or arbitrary values for these fields, ensure they are set by the application instead of user input.

References

• #167

0.7.1

Fixed

• Allow leading dot for domain (#174)
  • Although not permitted in the spec, some users expect this to work and user agents ignore the leading dot according to spec
• Add fast path for serialize without options, use obj.hasOwnProperty when parsing (#172)

v0.7.0...v0.7.1

0.7.0

• perf: parse cookies ~10% faster (#144 by @kurtextrem and #170)
• fix: narrow the validation of cookies to match RFC6265 (#167 by @bewinsnw)
• fix: add main to package.json for rspack (#166 by @proudparrot2)

v0.6.0...v0.7.0

0.6.0 (from changelog)

• Add partitioned option

0.5.0

• Add priority option
• Fix expires option to reject invalid dates
• pref: improve default decode speed
• pref: remove slow string split in parse

0.4.2

• pref: read value only when assigning in parse
• pref: remove unnecessary regexp in parse

0.4.1

• Fix maxAge option to reject invalid values

0.4.0

• Add SameSite=None support

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1.2.0 (from changelog)

• Add suppress argument

1.1.1 (from changelog)

• Work around Zlib close bug in Node.js < 4.5.5

1.1.0 (from changelog)

• Add Zlib steam support and Node.js leak work around

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2.0.0

Changed

• Align encoding with WHATWG URL spec (#8) be0f77b
  • Stops encoding \, ^, and |.

Important: If you are using this to encode user entered and validated URLs, upgrade to v2 immediately. It is possible to exploit \ encoding in v1. A URL can be formed that looks like http://foo.com\@bar.com, which parses as foo.com for the host, but when encodeUrl(url) will parse as bar.com for the host.

v1.0.2...v2.0.0

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See the full diff on Github. The new version differs by 21 commits:

• 2.0.0
• Use GitHub releases
• Update README, add behavior expectations
• Align encoding with WHATWG URL spec (#8)
• fix: typos in README.md (#6)
• build: eslint@5.11.1
• build: Node.js@11.6
• build: Node.js@10.15
• build: Node.js@8.15
• build: Node.js@6.16
• build: use yaml eslint configuration
• lint: apply standard 12 style
• tests: use strict equality
• build: support Node.js 11.x
• build: eslint-plugin-import@2.14.0
• build: support Node.js 10.x
• build: support Node.js 9.x
• build: Node.js@8.11
• build: Node.js@6.14
• build: Node.js@4.9
• lint: apply standard 11 style

1.2.1 (from changelog)

• Gracefully handle when handling an error and socket is null

1.2.0

• Remove set content headers that break response
• deps: on-finished@2.4.1
• deps: statuses@2.0.1
  • Rename 425 Unordered Collection to standard 425 Too Early

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See the full diff on Github. The new version differs by more commits than we can show here.

0.2.0

• Use req.socket over deprecated req.connection

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See the full diff on Github. The new version differs by more commits than we can show here.

See the full diff on Github. The new version differs by 18 commits:

• Update version to 1.9.1
• Include LICENSE file in published package
• Update TypeScript definitions.
• Bump version.
• Update compiled files.
• Add IPv6.toRFC5952String.
• Deprecate non-compliant functions
• Add IPv6.toFixedLengthString.
• Return RFC 5952 compliant string
• Bump version.
• Update Typescript range definitions in include 'unicast'.
• Bump version.
• CIDR array response reversed to properly deliminated string
• correct typescript definition for subnetMatch
• Fix validation of IPv4 four-part decimals containing individual zeroes
• Bump version.
• Add support for IPv4 trailing and leading zeros
• Reduced npm package size by excluding tests, bower and CI files

0.6.3 (from changelog)

• Revert "Lazy-load modules from main entry point"

0.6.2

• Fix sorting charset, encoding, and language with extra parameters

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1.3.3 (from changelog)

• Fix Node.js 0.8 return value inconsistencies

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See the full diff on Github. The new version differs by 35 commits:

• 1.3.3
• build: mocha@6.1.3
• build: speed up logic in Travis CI build steps
• lint: apply standard 12 style
• build: Node.js@11.14
• build: Node.js@10.15
• build: Node.js@8.15
• build: Node.js@6.17
• Fix Node.js 0.8 return value inconsistencies
• docs: switch badges to badgen
• build: Node.js@11.3
• build: Node.js@10.14
• build: Node.js@8.14
• build: Node.js@6.15
• build: eslint-plugin-import@2.14.0
• build: support Node.js 11.x
• build: Node.js@10.13
• build: Node.js@8.13
• build: eslint-plugin-import@2.13.0
• build: eslint-plugin-promise@3.8.0
• bench: add Node.js WHATWG URL
• build: support Node.js 10.x
• lint: apply standard 11 style
• build: Node.js@9.11
• build: Node.js@8.11
• build: Node.js@6.14
• build: Node.js@4.9
• build: Node.js@9.3
• build: use yaml eslint configuration
• build: eslint-plugin-promise@3.6.0
• build: eslint-plugin-node@5.2.1
• build: eslint-plugin-import@2.8.0
• build: support Node.js 9.x
• build: Node.js@8.9
• build: Node.js@6.12

🚨 Unpatched `path-to-regexp` ReDoS in 0.1.x

Impact

The regular expression that is vulnerable to backtracking can be generated in the 0.1.x release of path-to-regexp, originally reported in CVE-2024-45296

Patches

Upgrade to 0.1.12.

Workarounds

Avoid using two parameters within a single path segment, when the separator is not . (e.g. no /:a-:b). Alternatively, you can define the regex used for both parameters and ensure they do not overlap to allow backtracking.

References

• GHSA-9wv6-86v2-598j
• https://blakeembrey.com/posts/2024-09-web-redos/

🚨 path-to-regexp outputs backtracking regular expressions

Impact

A bad regular expression is generated any time you have two parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b.

Patches

For users of 0.1, upgrade to 0.1.10. All other users should upgrade to 8.0.0.

These versions add backtrack protection when a custom regex pattern is not provided:

• 0.1.10
• 1.9.0
• 3.3.0
• 6.3.0

They do not protect against vulnerable user supplied capture groups. Protecting against explicit user patterns is out of scope for old versions and not considered a vulnerability.

Version 7.1.0 can enable strict: true and get an error when the regular expression might be bad.

Version 8.0.0 removes the features that can cause a ReDoS.

Workarounds

All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b to /:a-:b([^-/]+).

If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length. For example, halving the attack string improves performance by 4x faster.

Details

Using /:a-:b will produce the regular expression /^\/([^\/]+?)-([^\/]+?)\/?$/. This can be exploited by a path such as /a${'-a'.repeat(8_000)}/a. OWASP has a good example of why this occurs, but the TL;DR is the /a at the end ensures this route would never match but due to naive backtracking it will still attempt every combination of the :a-:b on the repeated 8,000 -a.

Because JavaScript is single threaded and regex matching runs on the main thread, poor performance will block the event loop and can lead to a DoS. In local benchmarks, exploiting the unsafe regex will result in performance that is over 1000x worse than the safe regex. In a more realistic environment using Express v4 and 10 concurrent connections, this translated to average latency of ~600ms vs 1ms.

References

• OWASP
• Detailed blog post

0.1.12

Fixed

• Improved backtracking protection for 0.1.x, will break some previously valid paths (see previous advisory: GHSA-9wv6-86v2-598j)

v0.1.11...v0.1.12

0.1.10

Fixed

• Add backtrack protection to parameters 29b96b4
  • This will break some edge cases but should improve performance

v0.1.9...v0.1.10

0.1.9

Added

• Allow a non-lookahead regex (#312) c4272e4

component/path-to-regexp@v0.1.8...v0.1.9

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See the full diff on Github. The new version differs by 11 commits:

• 0.1.12
• Merge commit from fork
• 0.1.11
• Add error on bad input values
• 0.1.10
• Add backtrack protection to parameters
• Update repo url (#314)
• 0.1.9
• Allow a non-lookahead regex (#312)
• 0.1.8
• Add support for named matching groups (#301)

2.0.7

• deps: forwarded@0.2.0
  • Use req.socket over deprecated req.connection

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See the full diff on Github. The new version differs by more commits than we can show here.

See the full diff on Github. The new version differs by more commits than we can show here.

🚨 send vulnerable to template injection that can lead to XSS

Impact

passing untrusted user input - even after sanitizing it - to SendStream.redirect() may execute untrusted code

Patches

this issue is patched in send 0.19.0

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:

1. The attacker MUST control the input to response.redirect()
2. express MUST NOT redirect before the template appears
3. the browser MUST NOT complete redirection before:
4. the user MUST click on the link in the template

0.19.0

What's Changed

• Remove link renderization in html while redirecting (#235)

New Contributors

• @UlisesGascon made their first contribution in #235

Full Changelog: 0.18.0...0.19.0

0.18.0 (from changelog)

• Fix emitted 416 error missing headers property
• Limit the headers removed for 304 response
• deps: depd@2.0.0
  • Replace internal eval usage with Function constructor
  • Use instance methods on process to check for listeners
• deps: destroy@1.2.0
• deps: http-errors@2.0.0
  • deps: depd@2.0.0
  • deps: statuses@2.0.1
• deps: on-finished@2.4.1
• deps: statuses@2.0.1

0.17.2 (from changelog)

• pref: ignore empty http tokens
• deps: http-errors@1.8.1
  • deps: inherits@2.0.4
  • deps: toidentifier@1.0.1
  • deps: setprototypeof@1.2.0
• deps: ms@2.1.3

0.17.1 (from changelog)

• Set stricter CSP header in redirect & error responses
• deps: range-parser@~1.2.1

0.17.0 (from changelog)

• deps: http-errors@~1.7.2
  • Set constructor name when possible
  • Use toidentifier module to make class names
  • deps: depd@~1.1.2
  • deps: setprototypeof@1.1.1
  • deps: statuses@'>= 1.5.0 < 2'
• deps: mime@1.6.0
  • Add extensions for JPEG-2000 images
  • Add new font/* types from IANA
  • Add WASM mapping
  • Update .bdoc to application/bdoc
  • Update .bmp to image/bmp
  • Update .m4a to audio/mp4
  • Update .rtf to application/rtf
  • Update .wav to audio/wav
  • Update .xml to application/xml
  • Update generic extensions to application/octet-stream: .deb, .dll, .dmg, .exe, .iso, .msi
  • Use mime-score module to resolve extension conflicts
• deps: ms@2.1.1
  • Add week/w support
  • Fix negative number handling
• deps: statuses@~1.5.0
• perf: remove redundant path.normalize call

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🚨 serve-static vulnerable to template injection that can lead to XSS

Impact

passing untrusted user input - even after sanitizing it - to redirect() may execute untrusted code

Patches

this issue is patched in serve-static 1.16.0

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:

1. The attacker MUST control the input to response.redirect()
2. express MUST NOT redirect before the template appears
3. the browser MUST NOT complete redirection before:
4. the user MUST click on the link in the template

1.16.0

What's Changed

• Remove link renderization in html while redirecting (#173)

New Contributors

• @UlisesGascon made their first contribution in #173

Full Changelog: v1.15.0...1.16.0

1.15.0

• deps: send@0.18.0
  • Fix emitted 416 error missing headers property
  • Limit the headers removed for 304 response
  • deps: depd@2.0.0
  • deps: destroy@1.2.0
  • deps: http-errors@2.0.0
  • deps: on-finished@2.4.1
  • deps: statuses@2.0.1

1.14.2

• deps: send@0.17.2
  • deps: http-errors@1.8.1
  • deps: ms@2.1.3
  • pref: ignore empty http tokens

1.14.1 (from changelog)

• Set stricter CSP header in redirect response
• deps: send@0.17.1
  • deps: range-parser@~1.2.1

1.14.0

• deps: parseurl@~1.3.3
• deps: send@0.17.0
  • deps: http-errors@~1.7.2
  • deps: mime@1.6.0
  • deps: ms@2.1.1
  • deps: statuses@~1.5.0
  • perf: remove redundant path.normalize call

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