CVE-2026-55999: CWE-122 Heap-based buffer overflow in X.Org xorg-server
CVE-2026-55999 is a heap-based buffer overflow vulnerability in X.Org xorg-server and xwayland when processing PCX fonts via the SetFont request. It affects xorg-server versions before 21.2.24 and xwayland versions before 24.1.13. The flaw arises from missing glyph boundary checks. Local attackers with an X connection can trigger this overflow. The vulnerability has a high severity with a CVSS score of 8.5, impacting confidentiality, integrity, and availability. A patch is available to address this issue.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-55999) involves a heap-based buffer overflow in X.Org's xorg-server and xwayland components when handling PCX fonts through the SetFont request. The root cause is the absence of proper glyph boundary checks, which allows local attackers with an X connection to trigger memory corruption. This can lead to compromise of confidentiality, integrity, and availability of the affected system. The issue affects xorg-server versions prior to 21.2.24 and xwayland versions prior to 24.1.13. The CVSS 3.1 score is 8.5, indicating high severity. A fix has been released in the stated versions.
Potential Impact
Successful exploitation of this heap-based buffer overflow can allow a local attacker with an X connection to execute arbitrary code or cause denial of service, impacting confidentiality, integrity, and availability of the system running vulnerable versions of xorg-server or xwayland.
Mitigation Recommendations
A patch is available for this vulnerability. Users should upgrade xorg-server to version 21.2.24 or later and xwayland to version 24.1.13 or later to remediate this issue.
CVE-2026-55999: CWE-122 Heap-based buffer overflow in X.Org xorg-server
Description
CVE-2026-55999 is a heap-based buffer overflow vulnerability in X.Org xorg-server and xwayland when processing PCX fonts via the SetFont request. It affects xorg-server versions before 21.2.24 and xwayland versions before 24.1.13. The flaw arises from missing glyph boundary checks. Local attackers with an X connection can trigger this overflow. The vulnerability has a high severity with a CVSS score of 8.5, impacting confidentiality, integrity, and availability. A patch is available to address this issue.
CVSS v3.1
Score 8.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-55999) involves a heap-based buffer overflow in X.Org's xorg-server and xwayland components when handling PCX fonts through the SetFont request. The root cause is the absence of proper glyph boundary checks, which allows local attackers with an X connection to trigger memory corruption. This can lead to compromise of confidentiality, integrity, and availability of the affected system. The issue affects xorg-server versions prior to 21.2.24 and xwayland versions prior to 24.1.13. The CVSS 3.1 score is 8.5, indicating high severity. A fix has been released in the stated versions.
Potential Impact
Successful exploitation of this heap-based buffer overflow can allow a local attacker with an X connection to execute arbitrary code or cause denial of service, impacting confidentiality, integrity, and availability of the system running vulnerable versions of xorg-server or xwayland.
Mitigation Recommendations
A patch is available for this vulnerability. Users should upgrade xorg-server to version 21.2.24 or later and xwayland to version 24.1.13 or later to remediate this issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- suse
- Date Reserved
- 2026-06-18T09:26:55.988Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4e27eac9d9e3dbe3eaeaf2
Added to database: 07/08/2026, 10:35:22 UTC
Last enriched: 08/07/2026, 05:55:26 UTC
Last updated: 08/22/2026, 10:52:10 UTC
Views: 107
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