CVE-2026-3125 (GCVE-0-2026-3125)
Vulnerability from cvelistv5 – Published: 2026-03-04 18:14 – Updated: 2026-03-04 18:58
VLAI
EPSS
VEX
Title
SSRF vulnerability in opennextjs-cloudflare via /cdn-cgi/ path normalization bypass
Summary
A Server-Side Request Forgery (SSRF) vulnerability was identified in the @opennextjs/cloudflare package, resulting from a path normalization bypass in the /cdn-cgi/image/ handler.The @opennextjs/cloudflare worker template includes a /cdn-cgi/image/ handler intended for development use only. In production, Cloudflare's edge intercepts /cdn-cgi/image/ requests before they reach the Worker. However, by substituting a backslash for a forward slash (/cdn-cgi\image/ instead of /cdn-cgi/image/), an attacker can bypass edge interception and have the request reach the Worker directly. The JavaScript URL class then normalizes the backslash to a forward slash, causing the request to match the handler and trigger an unvalidated fetch of arbitrary remote URLs.
For example:
https://victim-site.com/cdn-cgi\image/aaaa/https://attacker.com
In this example, attacker-controlled content from attacker.com is served through the victim site's domain (victim-site.com), violating the same-origin policy and potentially misleading users or other services.
Note: This bypass only works via HTTP clients that preserve backslashes in paths (e.g., curl --path-as-is). Browsers normalize backslashes to forward slashes before sending requests.
Additionally, Cloudflare Workers with Assets and Cloudflare Pages suffer from a similar vulnerability. Assets stored under /cdn-cgi/ paths are not publicly accessible under normal conditions. However, using the same backslash bypass (/cdn-cgi\... instead of /cdn-cgi/...), these assets become publicly accessible. This could be used to retrieve private data. For example, Open Next projects store incremental cache data under /cdn-cgi/_next_cache, which could be exposed via this bypass.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-04 18:58 UTC
CWE
Assigner
References
4 references
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| opennextjs | @opennextjs/cloudflare |
Affected:
0 , < 1.17.1
(npm)
|
guessed |
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"other": {
"content": {
"id": "CVE-2026-3125",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-04T18:58:41.207814Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-04T18:58:46.967Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://www.npmjs.com/package/@opennextjs/cloudflare",
"defaultStatus": "unaffected",
"modules": [
"packages/cloudflare/src/cli/templates/worker.ts"
],
"packageName": "@opennextjs/cloudflare",
"platforms": [
"Cloudflare Workers"
],
"product": "@opennextjs/cloudflare",
"repo": "https://github.com/opennextjs/opennextjs-cloudflare",
"vendor": "opennextjs",
"versions": [
{
"lessThan": "1.17.1",
"status": "affected",
"version": "0",
"versionType": "npm"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "https://x.com/ez_z3r"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eA Server-Side Request Forgery (SSRF) vulnerability was identified in the @opennextjs/cloudflare package, resulting from a path normalization bypass in the /cdn-cgi/image/ handler.\u003c/span\u003e\u003cspan style=\"background-color: transparent;\"\u003eThe @opennextjs/cloudflare worker template includes a /cdn-cgi/image/ handler intended for development use only. In production, Cloudflare\u0027s edge intercepts /cdn-cgi/image/ requests before they reach the Worker. However, by substituting a backslash for a forward slash (/cdn-cgi\\image/ instead of /cdn-cgi/image/), an attacker can bypass edge interception and have the request reach the Worker directly. The JavaScript URL class then normalizes the backslash to a forward slash, causing the request to match the handler and trigger an unvalidated fetch of arbitrary remote URLs.\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eFor example: \u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003e\u003ca target=\"_blank\" rel=\"nofollow\" href=\"https://victim-site.com/cdn-cgi\\image/aaaa/https://attacker.com\"\u003ehttps://victim-site.com/cdn-cgi\\image/aaaa/https://attacker.com\u003c/a\u003e\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eIn this example, attacker-controlled content from attacker.com is served through the victim site\u0027s domain (victim-site.com), violating the same-origin policy and potentially misleading users or other services.\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eNote: This bypass only works via HTTP clients that preserve backslashes in paths (e.g., curl --path-as-is). Browsers normalize backslashes to forward slashes before sending requests.\u003c/span\u003e\u003c/p\u003e\u003cspan style=\"background-color: transparent;\"\u003eAdditionally, Cloudflare Workers with Assets and Cloudflare Pages suffer from a similar vulnerability. Assets stored under /cdn-cgi/ paths are not publicly accessible under normal conditions. However, using the same backslash bypass (/cdn-cgi\u003c/span\u003e\u003cspan style=\"background-color: transparent;\"\u003e\\.\u003c/span\u003e\u003cspan style=\"background-color: transparent;\"\u003e.. instead of /cdn-cgi/...), these assets become publicly accessible. This could be used to retrieve private data. For example, Open Next projects store incremental cache data under /cdn-cgi/_next_cache, which could be exposed via this bypass.\u003c/span\u003e\u003cbr\u003e"
}
],
"value": "A Server-Side Request Forgery (SSRF) vulnerability was identified in the @opennextjs/cloudflare package, resulting from a path normalization bypass in the /cdn-cgi/image/ handler.The @opennextjs/cloudflare worker template includes a /cdn-cgi/image/ handler intended for development use only. In production, Cloudflare\u0027s edge intercepts /cdn-cgi/image/ requests before they reach the Worker. However, by substituting a backslash for a forward slash (/cdn-cgi\\image/ instead of /cdn-cgi/image/), an attacker can bypass edge interception and have the request reach the Worker directly. The JavaScript URL class then normalizes the backslash to a forward slash, causing the request to match the handler and trigger an unvalidated fetch of arbitrary remote URLs.\n\nFor example: \n\n https://victim-site.com/cdn-cgi\\image/aaaa/https://attacker.com \n\nIn this example, attacker-controlled content from attacker.com is served through the victim site\u0027s domain (victim-site.com), violating the same-origin policy and potentially misleading users or other services.\n\nNote: This bypass only works via HTTP clients that preserve backslashes in paths (e.g., curl --path-as-is). Browsers normalize backslashes to forward slashes before sending requests.\n\nAdditionally, Cloudflare Workers with Assets and Cloudflare Pages suffer from a similar vulnerability. Assets stored under /cdn-cgi/ paths are not publicly accessible under normal conditions. However, using the same backslash bypass (/cdn-cgi\\... instead of /cdn-cgi/...), these assets become publicly accessible. This could be used to retrieve private data. For example, Open Next projects store incremental cache data under /cdn-cgi/_next_cache, which could be exposed via this bypass."
}
],
"impacts": [
{
"capecId": "CAPEC-664",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-664 Server Side Request Forgery"
}
]
},
{
"capecId": "CAPEC-267",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-267 Leverage Alternate Encoding"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 7.7,
"baseSeverity": "HIGH",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "HIGH",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:H/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-918",
"description": "CWE-918 Server-Side Request Forgery (SSRF)",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-706",
"description": "CWE-706 Use of Incorrectly-Resolved Name or Reference",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-03-04T18:14:31.111Z",
"orgId": "a22f1246-ba21-4bb4-a601-ad51614c1513",
"shortName": "cloudflare"
},
"references": [
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"tags": [
"patch"
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"url": "https://github.com/opennextjs/opennextjs-cloudflare/pull/1147"
},
{
"tags": [
"product"
],
"url": "https://www.npmjs.com/package/@opennextjs/cloudflare/v/1.17.1"
},
{
"tags": [
"related"
],
"url": "https://github.com/advisories/GHSA-rvpw-p7vw-wj3m"
},
{
"tags": [
"related"
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"url": "https://www.cve.org/cverecord?id=CVE-2025-6087"
}
],
"solutions": [
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"value": "\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eServer-side updates to Cloudflare\u0027s Workers platform to block backslash path normalization bypasses for /cdn-cgi requests. The update automatically mitigates the issue for all existing and any future sites deployed to Cloudflare Workers.\u003c/span\u003e\u003c/p\u003e\u003cbr\u003e\u003cbr\u003e"
}
],
"value": "Server-side updates to Cloudflare\u0027s Workers platform to block backslash path normalization bypasses for /cdn-cgi requests. The update automatically mitigates the issue for all existing and any future sites deployed to Cloudflare Workers."
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"supportingMedia": [
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"value": "\u003cp\u003e\u003cspan style=\"background-color: transparent;\"\u003eIn addition to the platform level fix, \u003c/span\u003e\u003ca target=\"_blank\" rel=\"nofollow\" href=\"https://github.com/opennextjs/opennextjs-cloudflare/pull/1147\"\u003e\u003cspan style=\"background-color: transparent;\"\u003eroot cause fix\u003c/span\u003e\u003c/a\u003e\u003cspan style=\"background-color: transparent;\"\u003e has been implemented to the Cloudflare adapter for Open Next. The patched version of the adapter is found at @opennextjs/cloudflare@1.17.1 (\u003c/span\u003e\u003ca target=\"_blank\" rel=\"nofollow\" href=\"https://www.npmjs.com/package/@opennextjs/cloudflare\"\u003e\u003cspan style=\"background-color: transparent;\"\u003ehttps://www.npmjs.com/package/@opennextjs/cloudflare\u003c/span\u003e\u003c/a\u003e\u003cspan style=\"background-color: transparent;\"\u003e)\u003c/span\u003e\u003c/p\u003e\u003cbr\u003e\u003cbr\u003e"
}
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"value": "In addition to the platform level fix, root cause fix https://github.com/opennextjs/opennextjs-cloudflare/pull/1147 has been implemented to the Cloudflare adapter for Open Next. The patched version of the adapter is found at @opennextjs/cloudflare@1.17.1 ( https://www.npmjs.com/package/@opennextjs/cloudflare https://www.npmjs.com/package/@opennextjs/cloudflare )"
},
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003ca target=\"_blank\" rel=\"nofollow\" href=\"https://github.com/opennextjs/opennextjs-cloudflare/pull/1150\"\u003e\u003cspan style=\"background-color: transparent;\"\u003eDependency update\u003c/span\u003e\u003c/a\u003e\u003cspan style=\"background-color: transparent;\"\u003e to the Next.js template used with create-cloudflare (c3) to use the fixed version of the Cloudflare adapter for Open Next.\u003c/span\u003e\u003cbr\u003e"
}
],
"value": "Dependency update https://github.com/opennextjs/opennextjs-cloudflare/pull/1150 to the Next.js template used with create-cloudflare (c3) to use the fixed version of the Cloudflare adapter for Open Next."
}
],
"source": {
"discovery": "UNKNOWN"
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"title": "SSRF vulnerability in opennextjs-cloudflare via /cdn-cgi/ path normalization bypass",
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"assignerShortName": "cloudflare",
"cveId": "CVE-2026-3125",
"datePublished": "2026-03-04T18:14:31.111Z",
"dateReserved": "2026-02-24T14:15:54.385Z",
"dateUpdated": "2026-03-04T18:58:56.614Z",
"state": "PUBLISHED"
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}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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