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fix(deps): update dependency next to v15.5.21 [security]#395

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fix(deps): update dependency next to v15.5.21 [security]#395
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renovate/npm-next-vulnerability

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@renovate renovate Bot commented Jul 24, 2026

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This PR contains the following updates:

Package Change Age Confidence
next (source) 15.5.1815.5.21 age confidence

Next.js: Cache confusion of response bodies for requests with bodies containing invalid UTF-8 byte sequences

CVE-2026-64647 / GHSA-4633-3j49-mh5q

More information

Details

Impact

A server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. Confidential data in the POST's response body would then leak to unauthorized requests. Though the request itself will not be deduped.

This is only an issue when receiving request bodies with a content type charset other than UTF-8. For example, the UTF-16 byte sequences for 삃삃 and 섄섄 in the request body would share the same cache.

Workarounds

If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js). Applications using Pages Router are not vulnerable.

Severity

  • CVSS Score: 6.3 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).


Next.js: Unbounded Server Action payload in Edge runtime

CVE-2026-64646 / GHSA-4c39-4ccg-62r3

More information

Details

Impact

Requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive memory consumption if that Server Actions uses the Edge runtime

Workarounds

If you cannot upgrade, ensure your hosting provider limits the request's body size. 5 MiB should be allowed at max by your hosting provider.

Severity

  • CVSS Score: 6.3 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).


Next.js: Cache confusion of response bodies for requests with bodies

CVE-2026-64648 / GHSA-68g3-v927-f742

More information

Details

Impact

A server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. Confidential data in the POST's response body would then leak to unauthorized requests. Though the request itself will not be deduped.

This only applies to fetch calls with a request that has a different init than the one passed to fetch.
Safe: fetch(new Request(init), init)
Unsafe: fetch(new Request(init), aDifferentInit)

Workarounds

No workaround exists besides upgrading. Applications using Pages Router are not vulnerable.

Severity

  • CVSS Score: 6.0 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).


Next.js: Server-Side Request Forgery in Server Actions on custom servers

CVE-2026-64649 / GHSA-89xv-2m56-2m9x

More information

Details

Impact

When a Server Action forwards or redirects a request, an attacker can cause the server to send that outbound request to a malicious host (Server-Side Request Forgery). This requires the attacker's request to control Host-associated headers. In some configurations, it's also possible to obtain internal values that weaken middleware/proxy authorization.

Applications that use Server Actions are affected when the incoming host header is not fixed to a trusted value. This typically occurs on custom servers, or on deployments not behind a proxy that pins the host. Managed hosting pins the host upstream and is not affected; next start and standalone output do the same from version 14.2 onward.

Workarounds

If you cannot upgrade, ensure clients do not control the host header your application receives. Pin or validate Host and X-Forwarded-Host at your edge or proxy. On version 14.2.0 and later, you can additionally set the __NEXT_PRIVATE_ORIGIN environment variable to your deployment's real origin:

__NEXT_PRIVATE_ORIGIN=https://www.example.com node server.js

#### Severity
- CVSS Score: 8.3 / 10 (High)
- Vector String: `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N`

#### References
- [https://github.com/vercel/next.js/security/advisories/GHSA-89xv-2m56-2m9x](https://redirect.github.com/vercel/next.js/security/advisories/GHSA-89xv-2m56-2m9x)
- [https://github.com/vercel/next.js/commit/b51206321854193208c0805ba42acc49287f942b](https://redirect.github.com/vercel/next.js/commit/b51206321854193208c0805ba42acc49287f942b)
- [https://github.com/vercel/next.js/commit/e3e5666ccead3a15162793d697af5e48b7cc0498](https://redirect.github.com/vercel/next.js/commit/e3e5666ccead3a15162793d697af5e48b7cc0498)
- [https://github.com/vercel/next.js](https://redirect.github.com/vercel/next.js)
- [https://github.com/vercel/next.js/releases/tag/v15.5.21](https://redirect.github.com/vercel/next.js/releases/tag/v15.5.21)
- [https://github.com/vercel/next.js/releases/tag/v16.2.11](https://redirect.github.com/vercel/next.js/releases/tag/v16.2.11)

This data is provided by [OSV](https://osv.dev/vulnerability/GHSA-89xv-2m56-2m9x) and the [GitHub Advisory Database](https://redirect.github.com/github/advisory-database) ([CC-BY 4.0](https://redirect.github.com/github/advisory-database/blob/main/LICENSE.md)).
</details>

---

### Next.js: Unauthenticated disclosure of internal Server Function endpoints
[CVE-2026-64643](https://nvd.nist.gov/vuln/detail/CVE-2026-64643) / [GHSA-955p-x3mx-jcvp](https://redirect.github.com/advisories/GHSA-955p-x3mx-jcvp)

<details>
<summary>More information</summary>

#### Details
##### Impact

In Next.js applications using App Router, Server Actions (`use server`) or `use cache` endpoints can be disclosed bypassing any authentication on the pages where these endpoints are usually used.

Server Action IDs can be disclosed to unauthenticated users via publicly served client artifacts (for example, static chunks containing action references).

Affected users are applications using App Router + Server Actions.  

By itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses.
 

##### Workarounds

Never assume any authentication claims at the `use cache` or `use server` boundary. Always authenticate within the boundary.

#### Severity
- CVSS Score: 6.3 / 10 (Medium)
- Vector String: `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`

#### References
- [https://github.com/vercel/next.js/security/advisories/GHSA-955p-x3mx-jcvp](https://redirect.github.com/vercel/next.js/security/advisories/GHSA-955p-x3mx-jcvp)
- [https://github.com/vercel/next.js/commit/1b0c3ae912a3ad925c60065cc8d55b070fa8bcd3](https://redirect.github.com/vercel/next.js/commit/1b0c3ae912a3ad925c60065cc8d55b070fa8bcd3)
- [https://github.com/vercel/next.js/commit/ff12a6124e1504f17b62de948b8a553fdecaef7b](https://redirect.github.com/vercel/next.js/commit/ff12a6124e1504f17b62de948b8a553fdecaef7b)
- [https://github.com/vercel/next.js](https://redirect.github.com/vercel/next.js)
- [https://github.com/vercel/next.js/releases/tag/v15.5.21](https://redirect.github.com/vercel/next.js/releases/tag/v15.5.21)
- [https://github.com/vercel/next.js/releases/tag/v16.2.11](https://redirect.github.com/vercel/next.js/releases/tag/v16.2.11)

This data is provided by [OSV](https://osv.dev/vulnerability/GHSA-955p-x3mx-jcvp) and the [GitHub Advisory Database](https://redirect.github.com/github/advisory-database) ([CC-BY 4.0](https://redirect.github.com/github/advisory-database/blob/main/LICENSE.md)).
</details>

---

### Next.js: Denial of Service in App Router using Server Actions
[CVE-2026-64641](https://nvd.nist.gov/vuln/detail/CVE-2026-64641) / [GHSA-m99w-x7hq-7vfj](https://redirect.github.com/advisories/GHSA-m99w-x7hq-7vfj)

<details>
<summary>More information</summary>

#### Details
##### Impact

Crafted requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive CPU usage blocking processing of further requests in the same process.

##### Workarounds

No workaround exists besides upgrading. Applications using Pages Router or not using Server Actions are not vulnerable.

#### Severity
- CVSS Score: 8.2 / 10 (High)
- Vector String: `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`

#### References
- [https://github.com/vercel/next.js/security/advisories/GHSA-m99w-x7hq-7vfj](https://redirect.github.com/vercel/next.js/security/advisories/GHSA-m99w-x7hq-7vfj)
- [https://github.com/vercel/next.js/pull/96013](https://redirect.github.com/vercel/next.js/pull/96013)
- [https://github.com/vercel/next.js/commit/019628571641dec57aaf349ba0c360e3964e6f12](https://redirect.github.com/vercel/next.js/commit/019628571641dec57aaf349ba0c360e3964e6f12)
- [https://github.com/vercel/next.js](https://redirect.github.com/vercel/next.js)
- [https://github.com/vercel/next.js/releases/tag/v15.5.21](https://redirect.github.com/vercel/next.js/releases/tag/v15.5.21)
- [https://github.com/vercel/next.js/releases/tag/v16.2.11](https://redirect.github.com/vercel/next.js/releases/tag/v16.2.11)

This data is provided by [OSV](https://osv.dev/vulnerability/GHSA-m99w-x7hq-7vfj) and the [GitHub Advisory Database](https://redirect.github.com/github/advisory-database) ([CC-BY 4.0](https://redirect.github.com/github/advisory-database/blob/main/LICENSE.md)).
</details>

---

### Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname
[CVE-2026-64645](https://nvd.nist.gov/vuln/detail/CVE-2026-64645) / [GHSA-p9j2-gv94-2wf4](https://redirect.github.com/advisories/GHSA-p9j2-gv94-2wf4)

<details>
<summary>More information</summary>

#### Details
##### Impact

A `rewrites()` or `redirects()` rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname, regardless of the rule's hostname suffix. For a rewrite, Next.js proxies the request to that arbitrary host and serves the response from the application's origin, leading to Server-Side Request forgery. A `redirects()` rule configured this way is vulnerable to an Open Redirect.

This affects any destination that puts a dynamic segment in the hostname, whether from the path:

```javascript
// next.config.js
module.exports = {
  async rewrites() {
    return [
      {
        source: '/:tenant',
        destination: 'https://:tenant.api.example.com',
      },
    ]
  },
}

or from a has capture:

// next.config.js
module.exports = {
  async rewrites() {
    return [
      {
        source: '/',
        has: [{ type: 'query', key: 'region', value: '(?<region>.+)' }],
        destination: 'https://:region.api.example.com',
      },
    ]
  },
}
Workarounds

If you cannot upgrade immediately, do not build the hostname of an external rewrites() or redirects() destination from user-controlled input. If a dynamic subdomain is required, constrain the value to hostname-safe characters: value: '(?<region>[a-z0-9-]+)'.

Severity

  • CVSS Score: 8.3 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).


Next.js: Denial of Service in the Image Optimization API using SVGs

CVE-2026-64644 / GHSA-q8wf-6r8g-63ch

More information

Details

Impact

When self-hosting Next.js with the default image loader, the Image Optimization API can optimize remotely hosted images if configured (not enabled by default). If those images contain malicious content, they can cause CPU exhaustion in /_next/image endpoints.

  • If you are using config.images.remotePatterns, only the patterns in that array are impacted.
  • If you are using config.images.unoptimized: true, you are NOT impacted.
  • If you are using config.images.loader: 'custom', you are NOT impacted.
  • If you are using Vercel, you are NOT impacted.
Workarounds

If you cannot upgrade immediately, you can avoid the expensive work by setting config.experimental.imgOptSkipMetadata : true.

Severity

  • CVSS Score: 6.3 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).


Release Notes

vercel/next.js (next)

v15.5.21

Compare Source

v15.5.20

Compare Source

Contains no changes except publishing @next/swc-wasm-web which was accidentally not published since 15.5.15.

v15.5.19: 15.5.19

Compare Source

[!NOTE]
This release is backporting bug fixes. It does not include all pending features/changes on canary.

Core Changes
  • [15.5.x] Don't drop FormData entries (#​94244)
Other
Credits

Huge thanks to @​eps1lon for helping!


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🚦 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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@vercel

vercel Bot commented Jul 24, 2026

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Project Deployment Actions Updated (UTC)
next-enterprise Ready Ready Preview, Comment Jul 24, 2026 5:55pm

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📦 Next.js Bundle Analysis for next-enterprise

This analysis was generated by the Next.js Bundle Analysis action. 🤖

🎉 Global Bundle Size Decreased

Page Size (compressed)
global 99.53 KB (🟢 -67 B)
Details

The global bundle is the javascript bundle that loads alongside every page. It is in its own category because its impact is much higher - an increase to its size means that every page on your website loads slower, and a decrease means every page loads faster.

Any third party scripts you have added directly to your app using the <script> tag are not accounted for in this analysis

If you want further insight into what is behind the changes, give @next/bundle-analyzer a try!

Four Pages Changed Size

The following pages changed size from the code in this PR compared to its base branch:

Page Size (compressed) First Load
/_not-found/page 995 B (🟢 9 B) 100.5 KB
/layout 3.23 KB (🟢 1 B) 102.76 KB
/api/health/route 127 B (🟢 1 B) 99.66 KB
/page 127 B (🟢 1 B) 99.66 KB
Details

Only the gzipped size is provided here based on an expert tip.

First Load is the size of the global bundle plus the bundle for the individual page. If a user were to show up to your website and land on a given page, the first load size represents the amount of javascript that user would need to download. If next/link is used, subsequent page loads would only need to download that page's bundle (the number in the "Size" column), since the global bundle has already been downloaded.

Any third party scripts you have added directly to your app using the <script> tag are not accounted for in this analysis

Next to the size is how much the size has increased or decreased compared with the base branch of this PR. If this percentage has increased by undefined% or more, there will be a red status indicator applied, indicating that special attention should be given to this.

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