CVE-2026-39244

adm-zip before 0.6.1 contains an incorrect permission assignment vulnerability that allows attackers to set setuid, setgid, or sticky bits on extracted files when keepOriginalPermission is enabled. Crafted zip external file attributes pass unmasked into chmod.

adm-zip before 0.6.1 contains an inconsistent entry resolution vulnerability that allows attackers to bypass content validation by supplying ZIP archives with duplicate entry names. getEntry() returns the last duplicate while extractAllTo() writes the first.

adm-zip 0.6.0 contains a decompression bomb protection bypass that allows attackers to evade the maxOutputLength guard by targeting the asynchronous getDataAsync() path in methods/inflater.js. Attackers can craft ZIP entries with falsified small declared sizes and high-ratio DEFLATE payloads to exhaust memory in applications reading entries asynchronously.

adm-zip before 0.6.1 contains a denial of service vulnerability that allows unauthenticated attackers to crash the Node.js process via a malformed ZIP file, because inflateAsync in methods/inflater.js lacks a zlib stream error listener. Attackers can supply a ZIP with corrupted DEFLATE data processed by readFileAsync, readAsTextAsync, extractAllToAsync, or getDataAsync, triggering an uncatchable exception that terminates all in-flight requests.

adm-zip prior to 0.6.1 applies Unix permission bits from a zip entry directly to the extracted file via fs.chmodSync() when keepOriginalPermission=true is passed to extractAllTo()/extractEntryTo() — and never filters out setuid/setgid/sticky bits. A crafted zip can produce an extracted binary with mode 04755, leading to attacker code execution as root when extraction runs as root.

A vulnerability in the adm-zip library (JavaScript) prior to 0.6.1 affects getData() in zipEntry.js, which trusts an entry's central-directory uncompressed size and allocates output memory before validating that value against the actual compressed data. A small crafted ZIP can declare a multi-gigabyte uncompressed size, causing excessive memory consumption before CRC validation reports an error. Applications reading entries from untrusted archives can be terminated by the OS or suffer memory exhaustion.

adm-zip versions 0.5.14 through 0.6.0 fail to apply zlib decompression output limits when ZIP entries declare zero uncompressed size. Attackers can craft malicious ZIP archives with highly compressible entries declaring zero size to exhaust memory and cause denial of service.

adm-zip 0.5.9 through 0.6.0 follows symbolic links at the extraction destination. Utils.sanitize enforces containment by comparing only the string form of an archive entry name against the resolved extraction root, and Utils.writeFileTo opens the computed destination with fs.openSync(path, "w", 0o666), which resolves symbolic links and carries neither O_NOFOLLOW nor a pre-write fs.lstatSync check. When a path component at the destination already exists as a symbolic link pointing outside the extraction root, extractAllTo, extractAllToAsync and extractEntryTo write the entry contents through that link and then chmod its target, placing attacker-controlled content in a file outside the root without any traversal sequence appearing in the archive. Reaching the write requires overwrite to be enabled, because the preceding fs.existsSync check also resolves the link and otherwise declines.