Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-55999— xorg-server / xwayland glamor font atlas Heap Buffer Overflow

Quick assessment

Affected
X.Org xorg-server
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

xorg xorg-server是xorg组织的一款服务器软件与操作系统组件。 xorg xorg-server 21.2.24之前版本存在缓冲区错误漏洞，该漏洞源于通过SetFont设置字体时缺少字形边界检查，可能导致本地攻击者利用X连接提供PCX字体，从而造成堆缓冲区溢出。

CVSS 8.5 · High EPSS 0.33% · P24

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 2

VendorProduct Version RangeStatus
X.Org xorg-server < 21.1.24 affected
X.Org xwayland < 24.1.13 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-55999

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
xorg-server / xwayland glamor font atlas Heap Buffer Overflow
Source: CVE Program / CVE List V5
Vulnerability Description
Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
xorg xorg-server 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
xorg xorg-server是xorg组织的一款服务器软件与操作系统组件。 xorg xorg-server 21.2.24之前版本存在缓冲区错误漏洞，该漏洞源于通过SetFont设置字体时缺少字形边界检查，可能导致本地攻击者利用X连接提供PCX字体，从而造成堆缓冲区溢出。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
X.Org xorg-server 0 ~ 21.1.24 -
X.Org xwayland 0 ~ 24.1.13 -

II. Public POCs for CVE-2026-55999

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-55999

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-55999 (1)

Mailing List Discussions for CVE-2026-55999 (1)

Same Patch Batch · X.Org · 2026-07-08 · 5 CVEs total

CVE-2026-56001 8.5 HIGH libXfont2 BitmapScaleBitmaps Integer Overflow Heap Buffer Overflow
CVE-2026-56002 8.5 HIGH libXfont2 PCF Font Parsing Heap Buffer Overflow
CVE-2026-56003 8.5 HIGH libXfont2 computeProps Property Buffer Heap Buffer Overflow
CVE-2026-56000 xorg-x11-server / xwayland GLX contextTags Use-After-Free in CommonMakeCurrent()

IV. Related Vulnerabilities

Same product: xorg-server
Same vendor: X.Org
Same weakness: CWE-122

V. Comments for CVE-2026-55999

No comments yet

Leave a comment