{"id":"CVE-2026-100409","aliases":["EUVD-2026-102200","GHSA-2vc4-c4r6-p6v6"],"status":"published","title":"OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths","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.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00493,"percentile":0.42789,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-177","CWE-180"],"published":"2026-10-15T16:57:50Z","modified":"2026-10-28T02:31:09Z","fixes":[{"ecosystem":"npm","package":"@opennextjs/cloudflare","fixed_in":["1.20.2"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@opennextjs/cloudflare","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.3.0"},{"fixed":"1.20.2"}]}]},{"source":"osv","ecosystem":"npm","package":"@opennextjs/cloudflare","ranges":[{"type":"SEMVER","events":[{"introduced":"0.3.0"},{"fixed":"1.20.2"}]}]}],"products":[{"vendor":"opennextjs","product":"opennextjs-cloudflare"}],"references":[{"url":"https://github.com/opennextjs/opennextjs-cloudflare/security/advisories/GHSA-2vc4-c4r6-p6v6","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/opennextjs/opennextjs-aws/pull/1199","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/opennextjs/opennextjs-aws/pull/1200","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/opennextjs/opennextjs-cloudflare/commit/38ea40b669be272ddf09a7df7e70c69d0b57404b","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/opennextjs/opennextjs-cloudflare/releases/tag/@opennextjs/cloudflare@1.20.2","tags":["x_refsource_MISC","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100409","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-2vc4-c4r6-p6v6"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100409.json","tags":["advisory"]},{"url":"https://github.com/opennextjs/opennextjs-cloudflare","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-100409","title":"OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths","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.","status":"published","published":"2026-10-15T16:57:50.999Z","modified":"2026-10-15T17:50:33.255Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-177","CWE-180"],"updated_at":"2026-11-02T14:20:06.925367Z"}],"euvd":[{"id":"EUVD-2026-102200","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.","status":"published","published":"2026-10-15T16:57:50Z","modified":"2026-10-15T17:50:33Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-02T17:00:11.403253Z"}],"ghsa":[{"id":"GHSA-2vc4-c4r6-p6v6","title":"OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths","description":"## Summary\n\nWhen cache interception is enabled, `@opennextjs/cloudflare` can interpret percent-encoded paths differently during middleware matching and cache lookup.\n\nAn encoded request may fail to match authorization middleware, then be decoded into the cache key of a protected route. The cached response may consequently be returned without invoking the middleware.\n\n`enableCacheInterception` is disabled by default.\n\n## Impact\n\nA remote unauthenticated attacker may retrieve cached content from routes intended to be protected by middleware.\n\nAn application is affected when it:\n\n- explicitly enables `enableCacheInterception`;\n- relies on middleware for access control; and\n- has a matching cached route.\n\n## Details\n\nMiddleware matching previously used the encoded request pathname, while cache interception decoded the pathname before selecting a cache entry.\n\nFor example, consider an application with:\n\n- middleware matcher `/admin/:path*`;\n- middleware returning `401 Authentication required` for `/admin`;\n- a statically generated, cached `/admin` route; and\n- cache interception enabled:\n\n```ts\nexport default defineCloudflareConfig({\n  incrementalCache: staticAssetsIncrementalCache,\n  enableCacheInterception: true,\n});\n```\n\nAn attacker can request:\n\n```http\nGET /%61dmin\n```\n\nThe encoded pathname does not match `/admin/:path*`, so the authorization middleware is not invoked. Cache interception then decodes `%61dmin` to `admin` and may return the cached `/admin` response:\n\n```http\nHTTP/1.1 200 OK\nx-opennext-cache: HIT\n\nProtected content\n```\n\nMalformed paths exposed an additional inconsistency. For example:\n\n```http\nGET /%61dmin/%ZZ\n```\n\nThe previous implementation decoded each segment independently. It decoded `%61dmin` to `admin` but retained the malformed `%ZZ` segment, allowing cache lookup to continue using a partially decoded pathname.\n\n## Patches\n\nThe fix aligns encoded-path handling across middleware matching and cache lookup, and rejects malformed paths instead of partially decoding them. See the upstream fixes in [opennextjs-aws#1199](https://github.com/opennextjs/opennextjs-aws/pull/1199) and [opennextjs-aws#1200](https://github.com/opennextjs/opennextjs-aws/pull/1200).\n\nUsers should upgrade to `@opennextjs/cloudflare@1.20.2` or later.\n\n## Workarounds\n\nIf upgrading is not immediately possible for an application:\n\n1. Disable cache interception by removing `enableCacheInterception: true`.\n2. Enforce authorization inside protected route handlers rather than relying exclusively on middleware.\n3. Reject encoded paths for protected routes at a trusted proxy before they reach the Worker.\n\nAdding individual encoded matcher variants is not a complete workaround because pathnames can have multiple equivalent encodings.","status":"published","published":"2026-10-15T20:15:17Z","modified":"2026-10-15T20:15:20Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-177","CWE-180"],"updated_at":"2026-11-02T14:41:32.483482Z"}],"nvd":[{"id":"CVE-2026-100409","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.","status":"published","published":"2026-10-15T17:17:07.923Z","modified":"2026-10-16T20:04:29.76Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-177","CWE-180"],"updated_at":"2026-11-02T14:12:59.751798Z"}],"osv":[{"id":"CVE-2026-100409","title":"OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths","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.","status":"published","published":"2026-10-15T16:57:50.999Z","modified":"2026-10-28T02:31:09.485179337Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-177","CWE-180"],"updated_at":"2026-11-02T15:44:53.490346Z"},{"id":"GHSA-2vc4-c4r6-p6v6","title":"OpenNext Cloudflare: Cache interception can bypass middleware protection for encoded paths","description":"## Summary\n\nWhen cache interception is enabled, `@opennextjs/cloudflare` can interpret percent-encoded paths differently during middleware matching and cache lookup.\n\nAn encoded request may fail to match authorization middleware, then be decoded into the cache key of a protected route. The cached response may consequently be returned without invoking the middleware.\n\n`enableCacheInterception` is disabled by default.\n\n## Impact\n\nA remote unauthenticated attacker may retrieve cached content from routes intended to be protected by middleware.\n\nAn application is affected when it:\n\n- explicitly enables `enableCacheInterception`;\n- relies on middleware for access control; and\n- has a matching cached route.\n\n## Details\n\nMiddleware matching previously used the encoded request pathname, while cache interception decoded the pathname before selecting a cache entry.\n\nFor example, consider an application with:\n\n- middleware matcher `/admin/:path*`;\n- middleware returning `401 Authentication required` for `/admin`;\n- a statically generated, cached `/admin` route; and\n- cache interception enabled:\n\n```ts\nexport default defineCloudflareConfig({\n  incrementalCache: staticAssetsIncrementalCache,\n  enableCacheInterception: true,\n});\n```\n\nAn attacker can request:\n\n```http\nGET /%61dmin\n```\n\nThe encoded pathname does not match `/admin/:path*`, so the authorization middleware is not invoked. Cache interception then decodes `%61dmin` to `admin` and may return the cached `/admin` response:\n\n```http\nHTTP/1.1 200 OK\nx-opennext-cache: HIT\n\nProtected content\n```\n\nMalformed paths exposed an additional inconsistency. For example:\n\n```http\nGET /%61dmin/%ZZ\n```\n\nThe previous implementation decoded each segment independently. It decoded `%61dmin` to `admin` but retained the malformed `%ZZ` segment, allowing cache lookup to continue using a partially decoded pathname.\n\n## Patches\n\nThe fix aligns encoded-path handling across middleware matching and cache lookup, and rejects malformed paths instead of partially decoding them. See the upstream fixes in [opennextjs-aws#1199](https://github.com/opennextjs/opennextjs-aws/pull/1199) and [opennextjs-aws#1200](https://github.com/opennextjs/opennextjs-aws/pull/1200).\n\nUsers should upgrade to `@opennextjs/cloudflare@1.20.2` or later.\n\n## Workarounds\n\nIf upgrading is not immediately possible for an application:\n\n1. Disable cache interception by removing `enableCacheInterception: true`.\n2. Enforce authorization inside protected route handlers rather than relying exclusively on middleware.\n3. Reject encoded paths for protected routes at a trusted proxy before they reach the Worker.\n\nAdding individual encoded matcher variants is not a complete workaround because pathnames can have multiple equivalent encodings.","status":"published","published":"2026-10-15T20:15:17Z","modified":"2026-10-15T20:30:05.349670038Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-177","CWE-180"],"updated_at":"2026-11-02T15:46:34.700741Z"}]}}