CVE-2026-40242: Github.com/getarcaneapp/arcane/backend Arcane Has Unauthenticated SSRF With Vulnerability
HIGHCVE-2026-40242 is a HIGH (CVSS 7.2) arcane has unauthenticated ssrf with vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Github.com/getarcaneapp/arcane/backend libraries in the Go ecosystem. The issue involves arcane has unauthenticated ssrf with conditional response reflection in template fetch endpoint. Remediation is available by upgrading affected packages to version 1.17.3.
CVE-2026-40242 at a Glance
Security Impact
CVSS: 7.2
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N).
How to Fix CVE-2026-40242
To remediate this vulnerability, upgrade all affected Github.com/getarcaneapp/arcane/backend dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/getarcaneapp/arcane/backend to 1.17.3Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/getarcaneapp/arcane/backendHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-40242, inspect your project dependencies for Github.com/getarcaneapp/arcane/backend:
inspect dependencies for github.com/getarcaneapp/arcane/backendAnalyze the terminal output to locate any version of Github.com/getarcaneapp/arcane/backend in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.17.3), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In Github.com/getarcaneapp/arcane/backend, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-40242 Affected Github.com/getarcaneapp/arcane/backend Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/getarcaneapp/arcane/backend
|
Go |
< 1.17.3
|
1.17.3
|
References
Frequently Asked Questions
What is CVE-2026-40242?
Which Github.com/getarcaneapp/arcane/backend versions are affected?
What version fixes CVE-2026-40242?
Is github.com/getarcaneapp/arcane/backend affected?
What is the CVSS score of CVE-2026-40242?
What CWE is associated with CVE-2026-40242?
How can I check Go dependencies for CVE-2026-40242?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-ff24-4prj-gpmj",
"modified" : "2026-07-21T14:02:57Z",
"published" : "2026-04-10T20:59:27Z",
"aliases" : [ "CVE-2026-40242" ],
"summary" : "Arcane has Unauthenticated SSRF with Conditional Response Reflection in Template Fetch Endpoint",
"details" : "### Summary\nThe /api/templates/fetch endpoint accepts a caller-supplied url parameter and performs a server-side HTTP GET request to that URL without authentication and without URL scheme or host validation. The server's response is returned directly to the caller. type. This constitutes an unauthenticated SSRF vulnerability affecting any publicly reachable Arcane instance.\n\n### Details\n- No allowlist or denylist of destination hosts/CIDRs\n- No requirement for the caller to be authenticated\n\nResponse handling produces four distinct outcomes observable by the caller: \n- Valid JSON targets return a fully reflected response body if the returned fields fit the expected internal struct\n- Non-JSON HTTP 200 responses produce an error leaking the first byte of the response (`\"Invalid JSON response: invalid character '<'...\"`)\n- Non-200 responses leak the HTTP status code\n- TCP-level failures distinguish between closed ports (`\"connection refused\"`) and filtered ones (`\"i/o timeout\"`)\n\n### PoC\nSend an unauthenticated GET request to `/api/templates/fetch`, passing the target URL as the `url` query parameter.\n\n<img width=\"1041\" height=\"375\" alt=\"image\" src=\"https://github.com/user-attachments/assets/f9fd475e-90b0-4dec-95e1-0af6263f5bb5\" />\n\n### Impact\n- Unauthenticated port scanning of internal networks\n- Access to internal HTTP services not exposed to the public internet (service discovery endpoints, internal dashboards, Kubernetes API)",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/getarcaneapp/arcane/backend"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.17.3"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 1.17.2"
}
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/getarcaneapp/arcane/security/advisories/GHSA-ff24-4prj-gpmj"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-40242"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/getarcaneapp/arcane"
}, {
"type" : "WEB",
"url" : "https://github.com/getarcaneapp/arcane/releases/tag/v1.17.3"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-918" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-04-10T20:59:27Z",
"nvd_published_at" : "2026-04-10T21:16:27Z"
}
}