Sourced from next's releases.

v12.0.9

This upgrade is completely backward-compatible and recommended for all users on versions below 12.0.9

Vulnerable code could allow a bad actor to trigger a denial of service attack via the /${locale}/_next/ route for anyone running a Next.js app at version >= 12.0.0, and using built-in i18n routing functionality.

How to Upgrade

• We have released patch versions for both the stable and canary channels of Next.js.
• To upgrade run npm install next@latest --save

Impact

• Affected: All of the following must be true to be affected by this CVE
  • Next.js versions between v12.0.0 and v12.0.9
  • Using next start or a custom server
  • Using the built-in i18n support
• Not affected:
  • Deployments on Vercel (vercel.com) are not affected along with similar environments where invalid requests are filtered before reaching Next.js.

We recommend everyone to upgrade regardless of whether you can reproduce the issue or not.

How to Assess Impact

If your server has seen requests to any route under the prefix /${locale}/_next/ that have triggered a heap overflow error, this was caused by the patched issue.

What is Being Done

As Next.js has grown in popularity and usage by enterprises, it has received the attention of security researchers and auditors. We are thankful to our users for their investigation and responsible disclosure of the original bug.

We've landed a patch that ensures this is handled properly so the requested route no longer crashes and triggers a heap overflow.

Regression tests for this attack were added to the i18n integration test suite

• A public CVE was released.
• We encourage responsible disclosure of future reports. Please email us at security@vercel.com. We are actively monitoring this mailbox.

Core Changes

• middlewares: limit process.env to inferred usage: #33186
• update webpack: #33207
• Abstract out native filesystem usage from the base server: #33226
• use text data url instead of base64 for shorter encoding: #33218
• chore(deps): upgrade postcss: #33142
• Fix global process testing for the process polyfill: #33220
• Update swc: #33201
• improve full refresh overlay: #33301
• Custom app for server components: #33149
• Update yarn PnP tests and disable swc file reading for PnP: #33236
• Base Http for BaseServer: #32999
• Update swc: #33342

... (truncated)

• 07431d3 v12.0.9
• c938e20 v12.0.9-canary.12
• c385d1b REMOVE: duplicate key in docs/testing.md (#33681)
• 9b98c5a chore(docs): update security headers specification (#33673)
• 865a079 v12.0.9-canary.11
• b5d4564 Revert "Relay Support in Rust Compiler" (#33699)
• 5c6c385 Use relative path for example (#33565)
• 65c63c9 v12.0.9-canary.10
• b20eb99 Relay Support in Rust Compiler (#33240)
• 99d4d6c Implement web server as the request handler for edge SSR (#33635)
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