cap-std doesn't fully sandbox all the Windows device filenames

### Impact cap-std's filesystem sandbox implementation on Windows blocks access to special device filenames such as "COM1", "COM2", "LPT0", "LPT1", and so on, however it did not block access to the special device filenames which use superscript digits, such as "COM¹", "COM²", "LPT⁰", "LPT¹", and so on. Untrusted filesystem paths could bypass the sandbox and access devices through those special device filenames with superscript digits, and through them provide access peripheral devices connected to the computer, or network resources mapped to those devices. This can include modems, printers, network printers, and any other device connected to a serial or parallel port, including emulated USB serial ports. ### Patches The bug is fixed in https://github.com/bytecodealliance/cap-std/pull/371, which is published in cap-primitives 3.4.1, cap-std 3.4.1, and cap-async-std 3.4.1. ### Workarounds There are no known workarounds for this issue. Affected Windows users are recommended to upgrade. ### References - [Microsoft's documentation](https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions) of the special device filenames - [ISO-8859-1](https://en.wikipedia.org/wiki/ISO/IEC_8859-1) - https://github.com/bytecodealliance/cap-std/pull/371

Source published

5 Nov 2024 22:19:59 UTC

Source modified

10 Sep 2026 03:50:20 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

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