CVE-2026-18736 Shlink Server-Side Request Forgery via Short URL Title Auto-Resolution
Authenticated attackers can exploit SSRF in Shlink to access internal services and cloud metadata via crafted URLs during short link creation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18736?
CVE-2026-18736 is a medium-severity server-side request forgery vulnerability in shlinkio Shlink, published on 3 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-918
Which versions are affected by CVE-2026-18736?
How do I fix CVE-2026-18736?
No fix has been published for CVE-2026-18736 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-18736 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-18736 exists.
Sources
Also known as GHSA-c6g4-pfhg-gvmp.