What is CVE-2026-18736?

CVE-2026-18736 is a medium-severity vulnerability in Shlinkio Shlink, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.0/10. Published 2026-08-03.

How severe is CVE-2026-18736?

Medium severity. CVSS v3 base score is 5.0 out of 10.

SSRF in Shlinkio Shlink

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.

Vulnerability class: SSRF (Server-Side Request Forgery)

EPSS: 0.003 (23.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N.

Affected products

Shlinkio Shlink — versions 2.6.0

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (product)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-18736?: CVE-2026-18736 is a medium-severity vulnerability in Shlinkio Shlink, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.0/10. Published 2026-08-03.
How severe is CVE-2026-18736?: Medium severity. CVSS v3 base score is 5.0 out of 10.