CVE-2026-100409 OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths
Attackers can bypass middleware authorization by using encoded paths to access cached protected content in OpenNext Cloudflare applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-100409?
CVE-2026-100409 is a high-severity authentication bypass vulnerability in opennextjs-cloudflare, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-100409?
2 open source packages ship an affected version, including @opennextjs/cloudflare.
| Package | Affected | Fixed in |
|---|---|---|
@opennextjs/cloudflare npm | From 0.3.0 | 1.20.2 |
@opennextjs/cloudflare npm | From 0.3.0 | 1.20.2 |
How do I fix CVE-2026-100409?
Upgrade @opennextjs/cloudflare to 1.20.2 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-100409 being exploited?
There is no known exploitation of CVE-2026-100409 in the wild and no public exploit code.
Sources
Also known as GHSA-2vc4-c4r6-p6v6.