What is CVE-2026-100409?

CVE-2026-100409 is a high-severity vulnerability in Opennextjs Opennextjs-Cloudflare, classified under CWE-177. CVSS score: 7.5/10. Published 2026-10-15.

How severe is CVE-2026-100409?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Opennextjs Opennextjs-Cloudflare

CVE-2026-100409

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.

Published 2026-10-15 · last modified 2026-10-15.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Opennextjs Opennextjs-Cloudflare — versions >= 0.3.0, < 1.20.2

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-100409?: CVE-2026-100409 is a high-severity vulnerability in Opennextjs Opennextjs-Cloudflare, classified under CWE-177. CVSS score: 7.5/10. Published 2026-10-15.
How severe is CVE-2026-100409?: High severity. CVSS v3 base score is 7.5 out of 10.