What’s Vulnerable › Vulnerabilities

CVE-2026-33644: Lychee has SSRF bypass via DNS rebinding — PhotoUrlRule only validates IP addresses, not hostnames resolving to internal IPs

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-26 · updated 2026-06-17
• Weakness: CWE-918

Description

Lychee is a free, open-source photo-management tool. Prior to version 7.5.2, the SSRF protection in `PhotoUrlRule.php` can be bypassed using DNS rebinding. The IP validation check (line 86-89) only activates when the hostname is an IP address. When a domain name is used, `filter_var($host, FILTER_VALIDATE_IP)` returns `false`, skipping the entire check. Version 7.5.2 patches the issue.

Affected products

• LycheeOrg Lychee: before 7.5.2 — fixed in 7.5.2

How to fix

Upgrade to a fixed version: LycheeOrg Lychee 7.5.2. Check the vendor advisory for mitigations.

References

• https://github.com/LycheeOrg/Lychee/commit/28c5261fb9deab4f9420c8cc2f73a87425939107
• https://github.com/LycheeOrg/Lychee/security/advisories/GHSA-5245-4p8c-jwff

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