CVE-2026-18736

Severity CVSS v4.0:

MEDIUM

Type:

CWE-918 Server-Side Request Forgery (SSRF)

Publication date:

03/08/2026

Last modified:

04/08/2026

Description

Shlink contains a server-side request forgery vulnerability that allows authenticated API key holders to cause the server to issue arbitrary HTTP GET requests by supplying a crafted long URL during short URL creation with title auto-resolution enabled. Attackers can submit URLs pointing to public hosts that redirect to internal targets, including loopback addresses, link-local ranges, and cloud metadata endpoints such as 169.254.169.254, to exfiltrate internal service information via the HTML title element returned in the short URL creation response.

Impact

Vector 4.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 5.30 MEDIUM
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): Low
User Interaction (UI): None
Confidentiality (VC): Low
Integrity (VI): None
Availability (VA): None
Confidentiality (SC): Low
Integrity (SI): None
Availability (SA): None

Base Score 4.0

5.30

Severity 4.0

MEDIUM

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.00 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): Low
Integrity (I): None
Availability (A): None

Base Score 3.x

5.00

Severity 3.x

MEDIUM

CVE-2026-18736

Description

Impact

References to Advisories, Solutions, and Tools