CVE-2026-40242

HighPublic PoC

Published: 10 April 2026

Published

10 April 2026

Modified

21 April 2026

KEV Added

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Patch

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CVSS Score 7.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

EPSS Score 0.0086 75.1th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-40242 is a high-severity SSRF (CWE-918) vulnerability in Getarcane Arcane. Its CVSS base score is 7.2 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 24.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-10 (Information Input Validation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Requires validation of the caller-supplied URL parameter at the /api/templates/fetch endpoint to prevent SSRF exploitation.

AC-3 Access Enforcement good match

prevent

Enforces authentication and authorization to block unauthenticated access to the vulnerable /api/templates/fetch endpoint.

SC-7 Boundary Protection partial match

preventdetect

Monitors and controls outbound communications at system boundaries to mitigate SSRF attempts to internal or arbitrary hosts.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1046 Network Service Discovery Discovery

Adversaries may attempt to get a listing of services running on remote hosts and local network infrastructure devices, including those that may be vulnerable to remote software exploitation.

attack.mitre.org →

Why these techniques?

Unauthenticated SSRF in public-facing Arcane app directly enables T1190 (Exploit Public-Facing Application). Ability to issue arbitrary internal HTTP requests and relay responses facilitates T1046 (Network Service Discovery) via port scanning and internal service interaction.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

Arcane is an interface for managing Docker containers, images, networks, and volumes. Prior to 1.17.3, the /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. This vulnerability is fixed in 1.17.3.

Deeper analysisAI

CVE-2026-40242 is an unauthenticated server-side request forgery (SSRF) vulnerability in Arcane, an interface for managing Docker containers, images, networks, and volumes. In versions prior to 1.17.3, the /api/templates/fetch endpoint accepts a caller-supplied URL parameter and performs a server-side HTTP GET request to that URL without requiring authentication, URL scheme validation, or host validation. The response from the requested server is then returned directly to the caller, enabling exploitation on any publicly reachable Arcane instance. The vulnerability is classified under CWE-918 with a CVSS v3.1 base score of 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N).

Any unauthenticated attacker with network access to a vulnerable Arcane instance can exploit this flaw by sending a crafted request to the /api/templates/fetch endpoint, tricking the server into making unintended HTTP requests to arbitrary URLs. This allows attackers to interact with internal services, conduct port scanning, or exfiltrate data from resources inaccessible from the public internet, as the server's response is relayed back to the attacker. The changed scope in the CVSS vector highlights the potential for impact beyond the vulnerable component itself.

The vulnerability is fixed in Arcane version 1.17.3, as detailed in the project's release notes and security advisory. Security practitioners should upgrade to v1.17.3 or later and review configurations to ensure Arcane instances are not publicly exposed unless necessary. Relevant resources include the GitHub release at https://github.com/getarcaneapp/arcane/releases/tag/v1.17.3 and the advisory at https://github.com/getarcaneapp/arcane/security/advisories/GHSA-ff24-4prj-gpmj.