CVE-2026-18736

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.

CVSS 4.0

5.3CVSS: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 3.1

5.0CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 26% of CVEs (scores of 2026-10-25)

CWE

CWE-918

Published

2026-08-03

Modified

2026-10-23

Record from

the NVD, synced 2026-10-24

References

• https://github.com/shlinkio/shlink
• https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-
• https://www.vulncheck.com/advisories/shlink-server-side-request-forgery-via-short-url-title-auto-resolution
• https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-

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