GHSA-cw26-7653-2rp5 exiftool-vendored vulnerable to argument injection via newline characters in tag names

• npm exiftool-vendored: < 35.19.0 → fixed in 35.19.0

Impact `exiftool-vendored` starts ExifTool in `-stay_open True -@ -` mode, where arguments are read from stdin one per line. In affected versions, several caller-supplied strings were interpolated into ExifTool arguments without rejecting line delimiters. A newline or carriage return inside one of those strings could split a single intended argument into multiple ExifTool arguments, allowing argument injection. The fix also rejects NUL bytes as unsafe control characters. Applications that pass attacker-controlled strings to affected APIs may allow an attacker to make ExifTool read files accessible to the ExifTool process, or write output to attacker-chosen file system paths accessible to that process. No remote code execution has been demonstrated. The reported write-path issue is caused by unsanitized tag keys. Tag values passed to `ExifTool#write` are not affected, because `WriteTask` already encodes whitespace characters in values (e.g. `\n` -> `&#10;`) before transmission. Confirmed affected inputs: • Tag-name arguments / tag keys — keys of the `tags` object passed to `ExifTool#write`; entries of the `retain` option to `ExifTool#deleteAllTags`; entries of the `numericTags` option to `ExifTool#read`; the `tagname` argument to `ExifTool#extractBinaryTag` and `#extractBinaryTagToBuffer`. • Filename / path arguments to `ExifTool#write`, `#read`, `#readRaw`, `#deleteAllTags`, `#rewriteAllTags`, `#extractBinaryTag`, `#extractBinaryTagToBuffer`, and the binary-extraction convenience methods `#extractJpgFromRaw`, `#extractPreview`, and `#extractThumbnail`. `path.resolve()` does not strip newlines, so an application that accepts attacker-controlled filenames containing newline characters was vulnerable. • The `imageHashType` option to `ExifTool#read`. TypeScript types restrict this to a literal union, but JS callers or callers with weakened type checking could reach the sink. Applications that only pass hardcoded strings for tag names, options, and filenames are not affected. Patches Fixed in v35.19.0. Two layers of defense: 1. Per-site input validation. A new `validateTagName` helper rejects any tag-name string containing characters outside the ExifTool tag grammar (letters, digits, `:`, `-`, `_`, and the ExifTool modifiers `*`, `?`, `+`, `#`). Applied at every tag-name interpolation site. 2. Defense-in-depth at the command renderer. `ExifToolTask.renderCommand` now rejects _any_ argument containing `\r`, `\n`, or `\0` before it is sent to the ExifTool process. This catches injection via filename arguments, option values, and any future interpolation site that forgets the per-site validator. Workarounds Upgrade to v35.19.0 or later. If upgrading immediately is not possible, reject untrusted strings containing control characters before passing them to the affected APIs. Conservative guard: ```ts function assertSafeForExifTool(s: string): void { if (typeof s !== "string" || /[\x00-\x20=<>]/.test(s)) { throw new Error("Rejected unsafe string for ExifTool"); } } ``` Apply to tag names, `retain` / `numericTags` entries, binary-extraction tag names, filenames, and the `imageHashType` option. This is a denylist and is strictly weaker than the library's internal validator; it is sufficient to block the known PoCs but will accept strings that the library itself now rejects. Resources • ExifTool `-stay_open` / argument-file documentation: https://exiftool.org/exiftool_pod.html#stay_open-FLAG • ExifTool tag-name reference: https://exiftool.org/TagNames/ • CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') — https://cwe.mitre.org/data/definitions/88.html Credit • Reporter: Hank Tam • Affiliation: Independent