A flaw was found in xorg-x11-server before 1.20.10. A heap-buffer overflow in XkbSetDeviceInfo may lead to a privilege escalation vulnerability. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Weakness
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| X_server | X.org | * | 1.20.10 (excluding) |
| Red Hat Enterprise Linux 7 | RedHat | xorg-x11-server-0:1.20.4-15.el7_9 | * |
| Red Hat Enterprise Linux 8 | RedHat | egl-wayland-0:1.1.5-3.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | libdrm-0:2.4.103-1.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | libglvnd-1:1.3.2-1.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | libinput-0:1.16.3-1.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | libwacom-0:1.6-2.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | libX11-0:1.6.8-4.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | mesa-0:20.3.3-2.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | xorg-x11-drivers-0:7.7-30.el8 | * |
| Red Hat Enterprise Linux 8 | RedHat | xorg-x11-server-0:1.20.10-1.el8 | * |
| Xorg | Ubuntu | trusty | * |
| Xorg-server | Ubuntu | bionic | * |
| Xorg-server | Ubuntu | devel | * |
| Xorg-server | Ubuntu | esm-infra-legacy/trusty | * |
| Xorg-server | Ubuntu | esm-infra/bionic | * |
| Xorg-server | Ubuntu | esm-infra/focal | * |
| Xorg-server | Ubuntu | esm-infra/xenial | * |
| Xorg-server | Ubuntu | focal | * |
| Xorg-server | Ubuntu | groovy | * |
| Xorg-server | Ubuntu | trusty | * |
| Xorg-server | Ubuntu | trusty/esm | * |
| Xorg-server | Ubuntu | xenial | * |
| Xorg-server-hwe-16.04 | Ubuntu | esm-infra/xenial | * |
| Xorg-server-hwe-16.04 | Ubuntu | xenial | * |
| Xorg-server-hwe-18.04 | Ubuntu | bionic | * |
| Xorg-server-hwe-18.04 | Ubuntu | esm-infra/bionic | * |
| Xorg-server-lts-utopic | Ubuntu | trusty | * |
| Xorg-server-lts-vivid | Ubuntu | trusty | * |
| Xorg-server-lts-wily | Ubuntu | trusty | * |
| Xorg-server-lts-xenial | Ubuntu | trusty | * |
Potential Mitigations
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
- D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
- Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
- Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
- For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].