X.Org Security Advisory: December 13, 2023 Issues in X.Org X server prior to 21.1.10 and Xwayland prior to 23.2.3 ========================================================================
Multiple issues have been found in the X server and Xwayland implementations published by X.Org for which we are releasing security fixes for in xorg-server-21.1.10 and xwayland-23.2.3. 1) CVE-2023-6377 can be triggered by forcing a logical device change on a device with buttons which will result in an out-of-bounds memory write. 2) CVE-2023-6478 can be triggered by sending a specially crafted request RRChangeProviderProperty or RRChangeOutputProperty. This will trigger an integer overflow and lead to disclosure of information. ------------------------------------------------------------------------ 1) CVE-2023-6377: X.Org server: Out-of-bounds memory write in XKB button actions Introduced in: xorg-server-1.6.0 (2009) Fixed in: xorg-server-21.1.10 and xwayland-23.2.3 Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/0c1a93d319558fe3ab2d94f51d174b4f93810afd Found by: Jan-Niklas Sohn working with Trend Micro Zero Day Initiative A device has XKB button actions for each button on the device. When a logical device switch happens (e.g. moving from a touchpad to a mouse), the server re-calculates the information available on the respective master device (typically the Virtual Core Pointer). This re-calculation only allocated enough memory for a single XKB action rather instead of enough for the newly active physical device's number of button. As a result, querying or changing the XKB button actions results in out-of-bounds memory reads and writes. This may lead to local privilege escalation if the server is run as root or remote code execution (e.g. x11 over ssh). xorg-server-21.1.10 and xwayland-23.2.3 have been patched to fix this issue. 2) CVE-2023-6478: X.Org server: Out-of-bounds memory read in RRChangeOutputProperty and RRChangeProviderProperty Introduced in: xorg-server-1.4.0 (2007) and xorg-server-1.13.0 (2012), respectively Fixed in: xorg-server-21.1.10 and xwayland-23.2.3 Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/14f480010a93ff962fef66a16412fafff81ad632 Found by: Jan-Niklas Sohn working with Trend Micro Zero Day Initiative This fixes an OOB read and the resulting information disclosure. Length calculation for the request was clipped to a 32-bit integer. With the correct stuff->nUnits value the expected request size was truncated, passing the REQUEST_FIXED_SIZE check. The server then proceeded with reading at least stuff->nUnits bytes (depending on stuff->format) from the request and stuffing whatever it finds into the property. In the process it would also allocate at least stuff->nUnits bytes, i.e. 4GB. See also CVE-2022-46344 where this issue was fixed for other requests. xorg-server-21.1.10 and xwayland-23.2.3 have been patched to fix this issue. ------------------------------------------------------------------------ X.Org thanks all of those who reported and fixed these issues, and those who helped with the review and release of this advisory and these fixes.
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