PT-2021-17199

CVE-2021-26958

تاريخ النشر

2021-02-04

تاريخ التحديث

2021-08-25

الوصف من

CVSS 3.1

8.8

عالية

المقاييسAV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions: xcb crate through 2021-02-04 for Rust

Description: The issue concerns a soundness violation in the xcb crate, which can lead to transmutation to the wrong type after using std::mem::transmute to return a reference to an arbitrary type. Specifically, the functions xcb::xproto::GetPropertyReply::value() and xcb::xproto::GetAtomNameReply::name() are affected. The value() function returns a slice of type T where T is an unconstrained type parameter, and the raw bytes received from the X11 server are interpreted as the requested type. The name() function calls std::str::from utf8 unchecked() on unvalidated bytes from an X server. Additionally, there is an out-of-bounds read in xcb::xproto::change property() when the format and type arguments do not match the intended use.

Recommendations: For the xcb crate through 2021-02-04 for Rust:

As a temporary workaround, consider restricting the use of the xcb::xproto::GetPropertyReply::value() function to only call it with the intended types, which are u8, u16, and u32.
Avoid using the xcb::xproto::GetAtomNameReply::name() function until the issue is resolved.
Restrict the use of the xcb::xproto::change property() function to only call it with one of the intended argument combinations, which are format = 8 and T = u8, format = 16 and T = u16, or format = 32 and T = u32.
Users are advised to only cast to the event structs provided by the xcb crate using the xcb::base::cast event() function. At the moment, there is no information about a newer version that contains a fix for this vulnerability.