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CVE-2025-4330 is an extraction-filter bypass in Python's tarfile module. When untrusted tar archives are extracted with TarFile.extractall() or TarFile.extract() using the "data" or "tar" filter, the filtering protections can be ignored, allowing symbolic-link targets outside the destination directory and modification of some file metadata. Usage relying on the default "data" filter in Python 3.14 or later is also affected when running a vulnerable release.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
Repository contains a working exploit generator for CVE-2025-4517 / CVE-2025-4330 affecting CPython’s tarfile.extractall(filter='data') safety checks. It provides two equivalent implementations (CVE-2025-4517.py and CVE-2025-4517.go) that generate a malicious tar archive (default: backup_99.tar). The exploit abuses a PATH_MAX (4096) overflow edge case in os.path.realpath(strict=False): when the resolved path becomes longer than PATH_MAX, realpath stops resolving symlinks and falls back to string-based path manipulation, causing Python’s tarfile “data” filter to incorrectly conclude a symlink remains within the extraction directory. Exploit structure (both implementations): (1) create 16 nested long-name directories plus 16 short 1-character symlinks (a–p) pointing to the long directories, so the logical path stays short while the resolved path grows; (2) add a 254-character symlink name at the end of the short chain that points back up 16 levels (".." x 16), pushing the resolved path over PATH_MAX; (3) create an 'escape' symlink whose link target traverses the short chain and then includes additional '..' components (DEPTH_TO_ROOT) intended to reach '/', which Python mis-validates due to the realpath fallback; (4) add a regular file entry at 'escape/<TARGET_FILE>' so extraction follows the OS-resolved symlink to write to '/<TARGET_FILE>' (default /root/.ssh/authorized_keys) with attacker-controlled content (default SSH public key placeholder). No network scanning or callbacks are present; the attack vector is delivery of a crafted tar to a workflow that extracts it with a vulnerable Python version. README.md documents affected versions, mechanics, configuration knobs (DEST_DIR/DEPTH_TO_ROOT/TARGET_FILE/PAYLOAD/OUTPUT), and expected post-exploitation outcome (e.g., root SSH access if extraction runs as root).
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A CPython tarfile extraction-filter bypass that can create links pointing outside the extraction directory.
A CPython tarfile extraction-filter bypass involving links that can reach outside the intended extraction directory.
A vulnerability addressed by the referenced TuxCare/AlmaLinux 9.2 local security advisory; no technical flaw details are provided.
A vulnerability addressed by the referenced CentOS 8.4 TuxCare security advisory; technical vulnerability details are not provided.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.