Red Hat Enterprise Linux 6/7/8/9 X.org X11 Server/TigerVNC XkbSizeKeySyms heap-based overflow

CVSS Meta Temp Score
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CTI Interest Score
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7.8$5k-$25k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Red Hat Enterprise Linux 6/7/8/9. This vulnerability affects the function XkbSizeKeySyms of the component X.org X11 Server/TigerVNC. Such manipulation leads to heap-based overflow. This vulnerability is documented as CVE-2025-26596. The attack needs to be performed locally. There is not any exploit available.

Detailsinfo

A vulnerability was found in Red Hat Enterprise Linux 6/7/8/9 and classified as critical. Affected by this issue is the function XkbSizeKeySyms of the component X.org X11 Server/TigerVNC. The manipulation with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. CVE summarizes:

A heap overflow flaw was found in X.Org and Xwayland. The computation of the length in XkbSizeKeySyms() differs from what is written in XkbWriteKeySyms(), which may lead to a heap-based buffer overflow.

The advisory is shared for download at access.redhat.com. This vulnerability is handled as CVE-2025-26596 since 02/12/2025. The exploitation is known to be easy. The attack needs to be approached locally. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 06/06/2026).

The vulnerability scanner Nessus provides a plugin with the ID 216902 (SUSE SLED15 / SLES15 / openSUSE 15 Security Update : xorg-x11-server (SUSE-SU-2025:0730-1)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (216902), EUVD (EUVD-2025-5403) and CERT Bund (WID-SEC-2025-0435). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • Gentoo Linux
  • IGEL OS
  • SUSE openSUSE
  • RESF Rocky Linux
  • OpenBSD OpenBSD
  • Dell NetWorker
  • Dell Avamar
  • Open Source X.Org X11
  • Open Source Xming
  • Dell PowerProtect Data Domain

Productinfo

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Vendor

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.8
VulDB Meta Temp Score: 7.8

VulDB Base Score: 7.8
VulDB Temp Score: 7.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

CNA Base Score: 7.8
CNA Vector (redhat): 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Heap-based overflow
CWE: CWE-122 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 216902
Nessus Name: SUSE SLED15 / SLES15 / openSUSE 15 Security Update : xorg-x11-server (SUSE-SU-2025:0730-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Timelineinfo

02/12/2025 🔍
02/25/2025 +13 days 🔍
02/25/2025 +0 days 🔍
06/06/2026 +466 days 🔍

Sourcesinfo

Vendor: redhat.com

Advisory: access.redhat.com
Status: Confirmed

CVE: CVE-2025-26596 (🔍)
GCVE (CVE): GCVE-0-2025-26596
GCVE (VulDB): GCVE-100-296816
EUVD: 🔍
CERT Bund: WID-SEC-2025-0435 - X.Org X11: Mehrere Schwachstellen ermöglichen nicht näher spezifizierte Auswirkungen, möglicherweise Codeausführung

Entryinfo

Created: 02/25/2025 18:23
Updated: 06/06/2026 03:43
Changes: 02/25/2025 18:23 (64), 02/27/2025 12:16 (2), 03/10/2025 14:28 (1), 06/16/2025 17:11 (1), 07/24/2025 18:47 (7), 06/06/2026 03:43 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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