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CVE Vulnerabilities

CVE-2025-26595

Stack-based Buffer Overflow

Published: Feb 25, 2025 | Modified: Nov 03, 2025
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2025-26595
CWEhttps://cwe.mitre.org/data/definitions/121.html

A buffer overflow flaw was found in X.Org and Xwayland. The code in XkbVModMaskText() allocates a fixed-sized buffer on the stack and copies the names of the virtual modifiers to that buffer. The code fails to check the bounds of the buffer and would copy the data regardless of the size.

Weakness

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Affected Software

NameVendorStart VersionEnd Version
TigervncTigervnc- (including)- (including)
Red Hat Enterprise Linux 10RedHatxorg-x11-server-Xwayland-0:24.1.5-3.el10_0*
Red Hat Enterprise Linux 7 Extended Lifecycle SupportRedHattigervnc-0:1.8.0-36.el7_9*
Red Hat Enterprise Linux 7 Extended Lifecycle SupportRedHatxorg-x11-server-0:1.20.4-30.el7_9*
Red Hat Enterprise Linux 8RedHattigervnc-0:1.13.1-15.el8_10*
Red Hat Enterprise Linux 8.2 Advanced Update SupportRedHattigervnc-0:1.9.0-15.el8_2.13*
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportRedHattigervnc-0:1.11.0-8.el8_4.12*
Red Hat Enterprise Linux 8.4 Telecommunications Update ServiceRedHattigervnc-0:1.11.0-8.el8_4.12*
Red Hat Enterprise Linux 8.4 Update Services for SAP SolutionsRedHattigervnc-0:1.11.0-8.el8_4.12*
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportRedHattigervnc-0:1.12.0-6.el8_6.13*
Red Hat Enterprise Linux 8.6 Telecommunications Update ServiceRedHattigervnc-0:1.12.0-6.el8_6.13*
Red Hat Enterprise Linux 8.6 Update Services for SAP SolutionsRedHattigervnc-0:1.12.0-6.el8_6.13*
Red Hat Enterprise Linux 8.8 Extended Update SupportRedHattigervnc-0:1.12.0-15.el8_8.12*
Red Hat Enterprise Linux 9RedHattigervnc-0:1.14.1-1.el9_5.1*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-0:1.20.11-28.el9_6*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-Xwayland-0:23.2.7-3.el9_6*
Red Hat Enterprise Linux 9.0 Update Services for SAP SolutionsRedHattigervnc-0:1.11.0-22.el9_0.13*
Red Hat Enterprise Linux 9.2 Extended Update SupportRedHattigervnc-0:1.12.0-14.el9_2.10*
Red Hat Enterprise Linux 9.4 Extended Update SupportRedHattigervnc-0:1.13.1-8.el9_4.5*
Xorg-serverUbuntudevel*
Xorg-serverUbuntuesm-infra/bionic*
Xorg-serverUbuntuesm-infra/focal*
Xorg-serverUbuntuesm-infra/xenial*
Xorg-serverUbuntufocal*
Xorg-serverUbuntujammy*
Xorg-serverUbuntunoble*
Xorg-serverUbuntuoracular*
Xorg-serverUbuntuplucky*
Xorg-serverUbuntuquesting*
Xorg-serverUbuntuupstream*
Xorg-server-hwe-16.04Ubuntuesm-infra/xenial*
Xorg-server-hwe-18.04Ubuntuesm-infra/bionic*
XwaylandUbuntudevel*
XwaylandUbuntujammy*
XwaylandUbuntunoble*
XwaylandUbuntuoracular*
XwaylandUbuntuplucky*
XwaylandUbuntuquesting*
XwaylandUbuntuupstream*

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].

References

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