CVE Vulnerabilities

CVE-2025-26596

Out-of-bounds Write

Published: Feb 25, 2025 | Modified: Mar 21, 2025
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
7.8 IMPORTANT
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Ubuntu
MEDIUM

A heap overflow flaw was found in X.Org and Xwayland. The computation of the length in XkbSizeKeySyms() differs from what is written in XkbWriteKeySyms(), which may lead to a heap-based buffer overflow.

Weakness

The product writes data past the end, or before the beginning, of the intended buffer.

Affected Software

Name Vendor Start Version End Version
Tigervnc Tigervnc - (including) - (including)
Red Hat Enterprise Linux 7 Extended Lifecycle Support RedHat tigervnc-0:1.8.0-36.el7_9 *
Red Hat Enterprise Linux 7 Extended Lifecycle Support RedHat xorg-x11-server-0:1.20.4-30.el7_9 *
Red Hat Enterprise Linux 8 RedHat tigervnc-0:1.13.1-15.el8_10 *
Red Hat Enterprise Linux 8.2 Advanced Update Support RedHat tigervnc-0:1.9.0-15.el8_2.13 *
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support RedHat tigervnc-0:1.11.0-8.el8_4.12 *
Red Hat Enterprise Linux 8.4 Telecommunications Update Service RedHat tigervnc-0:1.11.0-8.el8_4.12 *
Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions RedHat tigervnc-0:1.11.0-8.el8_4.12 *
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support RedHat tigervnc-0:1.12.0-6.el8_6.13 *
Red Hat Enterprise Linux 8.6 Telecommunications Update Service RedHat tigervnc-0:1.12.0-6.el8_6.13 *
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions RedHat tigervnc-0:1.12.0-6.el8_6.13 *
Red Hat Enterprise Linux 8.8 Extended Update Support RedHat tigervnc-0:1.12.0-15.el8_8.12 *
Red Hat Enterprise Linux 9 RedHat tigervnc-0:1.14.1-1.el9_5.1 *
Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions RedHat tigervnc-0:1.11.0-22.el9_0.13 *
Red Hat Enterprise Linux 9.2 Extended Update Support RedHat tigervnc-0:1.12.0-14.el9_2.10 *
Red Hat Enterprise Linux 9.4 Extended Update Support RedHat tigervnc-0:1.13.1-8.el9_4.5 *
Xorg-server Ubuntu devel *
Xorg-server Ubuntu esm-infra/bionic *
Xorg-server Ubuntu esm-infra/xenial *
Xorg-server Ubuntu focal *
Xorg-server Ubuntu jammy *
Xorg-server Ubuntu noble *
Xorg-server Ubuntu oracular *
Xorg-server Ubuntu upstream *
Xorg-server-hwe-16.04 Ubuntu esm-infra/xenial *
Xorg-server-hwe-18.04 Ubuntu esm-infra/bionic *
Xwayland Ubuntu devel *
Xwayland Ubuntu jammy *
Xwayland Ubuntu noble *
Xwayland Ubuntu oracular *
Xwayland Ubuntu upstream *

Potential Mitigations

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  • For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

  • Be wary that a language’s interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  • Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

  • 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.

  • Consider adhering to the following rules when allocating and managing an application’s memory:

  • 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].

  • Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

  • For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

References