CVE-2026-48707

InstantCMS vulnerable to SSRF via upload redirect bypass allows internal network service scanning

LOW
3.1
CVSS Score
Published: September 8, 2026 at 05:26 PM UTC
Updated: September 11, 2026 at 09:17 PM UTC
1 product affected across 1 vendorInstantcms

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Severity
LOW3.1
Exploit prediction
EPSS 0.3%
SSVC
PoC

Description

InstantCMS is a free and open source content management system. Versions prior to 2.18.2 have a Server-Side Request Forgery (SSRF) vulnerability in the file upload functionality (`system/core/uploader.php` at lines 509-532). When the "upload from URL" feature follows an HTTP redirect, the redirected target URL bypasses the private IP address blacklist check. This allows authenticated users to scan and access internal network services. Version 2.18.2 contains a fix.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.18.2
Affected range stops below 2.18.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.1LOWGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-918

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