Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2026-50259

Stack-based Buffer Overflow

Published: Jun 05, 2026 | Modified: Jun 25, 2026
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
Vulnerability-free packages from our partners
root.io logo minimus.io logo echo.ai logo
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-50259
CWEhttps://cwe.mitre.org/data/definitions/121.html

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.

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
X_serverX.org*21.1.23 (excluding)
XwaylandX.org*24.1.12 (excluding)
Enterprise_linuxRedhat7.0 (including)7.0 (including)
Enterprise_linuxRedhat8.0 (including)8.0 (including)
Enterprise_linuxRedhat9.0 (including)9.0 (including)
Enterprise_linuxRedhat10.0 (including)10.0 (including)
Red Hat Enterprise Linux 10RedHatxorg-x11-server-Xwayland-0:24.1.9-4.el10_2.2*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-Xwayland-0:21.1.3-20.el8_10.2*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-0:1.20.11-28.el8_10.2*
Red Hat Enterprise Linux 8RedHattigervnc-0:1.15.0-10.el8_10*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.2*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-0:1.20.11-34.el9_8.2*
Red Hat Enterprise Linux 9RedHattigervnc-0:1.15.0-7.el9_8.2*
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

Aqua Security is the largest pure-play cloud native security company, providing customers the freedom to innovate and run their businesses with minimal friction. The Aqua Cloud Native Security Platform provides prevention, detection, and response automation across the entire application lifecycle to secure the build, secure cloud infrastructure and secure running workloads wherever they are deployed.
Copyright © 2026 Aqua Security Software Ltd.   Privacy Policy | Terms of Use