CVE-2026-18736

Published: Aug 3, 2026Modified: Sep 9, 2026Deferred

5.3

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XShow less

Source: disclosure@vulncheck.com (Secondary)

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.

Related CWEs

CWE-918

Server-Side Request Forgery (SSRF)

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.

References (4)

https://github.com/shlinkio/shlink

Source: disclosure@vulncheck.com

https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-

Source: disclosure@vulncheck.com

https://www.vulncheck.com/advisories/shlink-server-side-request-forgery-via-short-url-title-auto-resolution

Source: disclosure@vulncheck.com

https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Timeline

No history available yet.