CVE-2026-33537 Lychee has SSRF bypass via incomplete IP validation in Photo::fromUrl — loopback and link-local IPs not blocked

Medium 5.3 Published 26 Mar 2026 Updated 27 Mar 2026

Authenticated users can bypass SSRF protections to access internal services via loopback or link-local IPs in Lychee.

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-2026-33537?

CVE-2026-33537 is a medium-severity server-side request forgery vulnerability in LycheeOrg Lychee, published on 26 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Lychee is a free, open-source photo-management tool. The patch introduced for GHSA-cpgw-wgf3-xc6v (SSRF via `Photo::fromUrl`) contains an incomplete IP validation check that fails to block loopback addresses and link-local addresses. Prior to version 7.5.1, an authenticated user can still reach internal services using direct IP addresses, bypassing all four protection configuration settings even when they are set to their secure defaults. Version 7.5.1 contains a fix for the issue.

Weakness: CWE-918

Which versions are affected by CVE-2026-33537?

It affects 1 product.

Products include Lycheeorg Lychee.

How do I fix CVE-2026-33537?

No fix has been published for CVE-2026-33537 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-2026-33537 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33537 exists.

Sources

Also known as GHSA-vq6w-prpf-h287.