CVE-2026-33644 PUBLISHED

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

Assigner: GitHub_M
Reserved: 23.03.2026 Published: 26.03.2026 Updated: 26.03.2026

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.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
CVSS Score: 2.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	Low	Confidentiality	Low
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	Low
User Interaction	None

CVSS 4.0

Product Status

Vendor	LycheeOrg
Product	Lychee
Versions	Version < 7.5.2 is affected

References

Problem Types

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