Affected: shell-quote

shell-quote's `quote()` function emits a `{ comment }` token as `#` followed by its text, which comments out the rest of the shell line, including the opening quote of any later string token. A line terminator (\n, \r, U+2028, U+2029) in that later string therefore ends the comment, and the rest of the string is parsed as shell input: `quote(['echo', 'ok', { comment: 'x' }, 'a\nid;#'])` runs `id` in sh, bash, dash, ksh and zsh. `parse()` emits a comment token for a `#` in the middle of a word (for example `http://example.com/#frag`), so callers that combine `parse()` output with another untrusted string, such as `quote(parse(untrustedCommand).concat(untrustedArg))`, are affected. The fix for CVE-2026-9277 rejected line terminators in the comment's own text, but not in the tokens after it. Fixed in 1.11.0: `quote()` throws a `TypeError` when a string after a `{ comment }` token contains a line terminator.

Affected: npm: shell-quote

### Impact

`quote()` emits a `{ comment }` token as `#` followed by its text, which comments out the rest of the shell line, including the opening quote of any later string token. A line terminator in that later string ends the comment, and the rest of the string is parsed as shell input:

```js quote(['echo', 'ok', { comment: 'x' }, 'a\nid;#']); // echo ok #x 'a // id;#' ```

Passed to `sh`, `bash`, `dash`, `ksh`, or `zsh`, this runs `id`.

`parse()` emits a comment token for a `#` in the middle of a word (for example `http://example.com/#frag`), so callers that combine `parse()` output with another untrusted string, such as `quote(parse(untrustedCommand).concat(untrustedArg))`, are affected. The fix for CVE-2026-9277 rejected line terminators in the comment's own text, but not in the tokens after it.

Exploitation requires an attacker-controlled string containing a line terminator that follows a `{ comment }` token in the same `quote()` call.

### Patches

Fixed in v1.11.0: `quote()` throws a `TypeError` when a string after a `{ comment }` token contains a line terminator (`\n`, `\r`, U+2028, or U+2029).

### Workarounds

Drop every token after a `{ comment }` token before calling `quote()`, or reject line terminators in untrusted strings. Separately, do not append other shell text after `quote()` output that contains a comment, since the comment swallows it.