CVE-2026-56003
libXfont2 computeProps Property Buffer Heap Buffer Overflow
Description
A heap buffer overflow due to missing size checking in the property buffer when parsing PCF files in libXfont2 ComputeScaledProperties() before libXfont2 before 2.0.8 could be used by attackers using authenticated X clients to execute code within the X server.
INFO
Published Date :
July 8, 2026, 10:16 a.m.
Last Modified :
July 9, 2026, 7:50 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 404e59f5-483d-4b8a-8e7a-e67604dd8afb | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update libXfont2 to version 2.0.8 or later.
- Apply vendor-provided patches for libXfont2.
- Recompile libXfont2 with updated source code.
Public PoC/Exploit Available at Github
CVE-2026-56003 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-56003.
| URL | Resource |
|---|---|
| https://gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/dff957a5158da038a282a59a31fe736702732939 | Patch |
| https://www.openwall.com/lists/oss-security/2026/07/08/1 | Mailing List Patch Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56003 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-56003
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
DSA and DLA for Debian last 14 days
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56003 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56003 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Reanalysis by [email protected]
Jul. 09, 2026
Action Type Old Value New Value Changed CPE Configuration OR *cpe:2.3:a:x:libxfont:*:*:*:*:*:*:*:* versions up to (excluding) 2.0.8 OR *cpe:2.3:a:x:libxfont:*:*:*:*:*:*:*:* versions from (including) 2.0.0 up to (excluding) 2.0.8 -
Initial Analysis by [email protected]
Jul. 09, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:x:libxfont:*:*:*:*:*:*:*:* versions up to (excluding) 2.0.8 Added Reference Type SUSE: https://gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/dff957a5158da038a282a59a31fe736702732939 Types: Patch Added Reference Type SUSE: https://www.openwall.com/lists/oss-security/2026/07/08/1 Types: Mailing List, Patch, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 09, 2026
Action Type Old Value New Value Changed SSVC {'id': 'CVE-2026-56003', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-08T12:06:32.424595Z'} {'id': 'CVE-2026-56003', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-08T00:00:00+00:00'} -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 08, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-56003', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-08T12:06:32.424595Z'} -
New CVE Received by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://gitlab.freedesktop.org/xorg/lib/libxfont/', 'vendor': 'X.Org', 'product': 'libXfont2', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.0.8', 'versionType': 'rpm'}], 'packageName': 'libXfont2', 'defaultStatus': 'unaffected'}] Added Description A heap buffer overflow due to missing size checking in the property buffer when parsing PCF files in libXfont2 ComputeScaledProperties() before libXfont2 before 2.0.8 could be used by attackers using authenticated X clients to execute code within the X server. Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H Added CWE CWE-122 Added Reference https://gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/dff957a5158da038a282a59a31fe736702732939 Added Reference https://www.openwall.com/lists/oss-security/2026/07/08/1