Multiple issues involving quote API

## Issue 1: Failure to quote characters Affected versions of this crate allowed the bytes `{` and `\xa0` to appear unquoted and unescaped in command arguments. If the output of `quote` or `join` is passed to a shell, then what should be a single command argument could be interpreted as multiple arguments. This does not *directly* allow arbitrary command execution (you can't inject a command substitution or similar). But depending on the command you're running, being able to inject multiple arguments where only one is expected could lead to undesired consequences, potentially including arbitrary command execution. The flaw was corrected in version 1.2.1 by escaping additional characters. Updating to 1.3.0 is recommended, but 1.2.1 offers a more minimal fix if desired. Workaround: Check for the bytes `{` and `\xa0` in `quote`/`join` input or output. (Note: `{` is problematic because it is used for glob expansion. `\xa0` is problematic because it's treated as a word separator in [specific environments][solved-xa0].) ## Issue 2: Dangerous API w.r.t. nul bytes Version 1.3.0 deprecates the `quote` and `join` APIs in favor of `try_quote` and `try_join`, which behave the same except that they have `Result` return type, returning `Err` if the input contains nul bytes. Strings containing nul bytes generally cannot be used in Unix command arguments or environment variables, and most shells cannot handle nul bytes even internally. If you try to pass one anyway, then the results might be security-sensitive in uncommon scenarios. [More details here.][nul-bytes] Due to the low severity, the behavior of the original `quote` and `join` APIs has not changed; they continue to allow nuls. Workaround: Manually check for nul bytes in `quote`/`join` input or output. ## Issue 3: Lack of documentation for interactive shell risks The `quote` family of functions does not and cannot escape control characters. With non-interactive shells this is perfectly safe, as control characters have no special effect. But if you writing directly to the standard input of an interactive shell (or through a pty), then control characters [can cause misbehavior including arbitrary command injection.][control-characters] This is essentially unfixable, and has not been patched. But as of version 1.3.0, documentation has been added. Future versions of `shlex` may add API variants that avoid the issue at the cost of reduced portability. [solved-xa0]: https://docs.rs/shlex/latest/shlex/quoting_warning/index.html#solved-xa0 [nul-bytes]: https://docs.rs/shlex/latest/shlex/quoting_warning/index.html#nul-bytes [control-characters]: https://docs.rs/shlex/latest/shlex/quoting_warning/index.html#control-characters-interactive-contexts-only

Source published

21 Jan 2024 12:00:00 UTC

Source modified

12 Oct 2026 18:00:05 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

OSV · upstream source license applies

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