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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain local low-privileged account
  2. Delivery
    Open X11 connection to server
  3. Exploit
    Craft malformed GLX ChangeDrawableAttributes request
  4. Execution
    Trigger out-of-bounds read in __glXDisp_ChangeDrawableAttributes()
  5. Impact
    Receive leaked server memory contents

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires local system access with at minimum a low-privileged user account (CVSS PR:L, AV:L) - remote unauthenticated exploitation is not possible. The attacker must be able to open a connection to the X server, which typically means they must be logged into the system locally or via an authenticated remote session (e.g., SSH with X11 forwarding enabled). The X server must have the GLX extension loaded, which is enabled by default in most X.Org configurations. The more severe write path is additionally gated by byte-swapped client mode, which is disabled by default and requires explicit non-standard server configuration to be reachable. Exploitation is limited to memory disclosure from the X server process; no code execution or privilege escalation is achievable via the read path alone.

Impact

The CVSS 3.1 base score of 5.5 (Medium) reflects a constrained attack surface: AV:L requires local system access, PR:L requires at minimum a low-privileged user account, and the scope is unchanged (S:U), meaning the impact is contained to the X server process itself. The high confidentiality impact (C:H) is offset by no integrity (I:N) or availability (A:N) impact, consistent with a read-only memory disclosure primitive. No EPSS data was provided in the source intelligence, so exploitation probability cannot be quantified. The vulnerability is not listed in CISA KEV and no public proof-of-concept code has been identified, confirming no confirmed active exploitation at time of analysis. The write path, while potentially more dangerous, requires byte-swapped clients - a non-default configuration - which materially limits real-world exploitability of that variant. Overall, this is a medium-priority local information disclosure: meaningful in hardened multi-user environments or containers running X11, but not an urgent emergency patch for most deployments.

Exploit ScenarioDerived

A local user with a standard unprivileged account on a system running X.Org X server or Xwayland crafts a malformed ChangeDrawableAttributes GLX protocol request with a size field larger than the actual request buffer. Upon submission to the X server, __glXDisp_ChangeDrawableAttributes() reads beyond the request buffer boundary and returns excess memory contents to the client, potentially leaking heap data including X server state, other clients' data, or sensitive information processed in the server's address space. No public proof-of-concept code is known, but the attack requires no special tooling beyond the ability to open an X11 connection.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 05, 2026

Out-of-bounds read in X.Org X server and Xwayland's GLX extension handler __glXDisp_ChangeDrawableAttributes() allows a local low-privileged user to disclose sensitive memory contents from the X server process. Faulty size validation permits reading a client-controlled number of bytes beyond the request buffer boundary, resulting in high confidentiality impact per CVSS. A secondary write path exists in the same function but is gated behind byte-swapped client support, which is disabled by default, substantially limiting its practical exposure. No public exploit code and no CISA KEV listing have been identified at time of analysis.

RemediationAI

The upstream fix is available via commit 6d459e4daf715bea8abdafa8fb130be2f8a1d145 in the xorg/xserver GitLab repository (https://gitlab.freedesktop.org/xorg/xserver/-/commit/6d459e4daf715bea8abdafa8fb130be2f8a1d145); an exact tagged release version was not independently confirmed from the available data - monitor the xorg-announce list post (https://lists.x.org/archives/xorg-announce/2026-June/003702.html) and the Red Hat advisory (https://access.redhat.com/security/cve/CVE-2026-50262) for distribution-specific update packages. As a compensating control where patching is delayed, administrators can restrict local user access to the X server socket (e.g., via Xwrapper.config or SELinux policy) to reduce the population of users able to submit crafted GLX requests - note this may break legitimate graphical application access. Disabling the GLX extension entirely (-noglx server flag) eliminates the vulnerable code path but will prevent all OpenGL-based applications from functioning. Byte-swapped client support, which gates the write path, is already disabled by default and should not be re-enabled.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability resides in the GLX (OpenGL Extension to the X Window System) protocol dispatch layer within the X.Org X server and its Wayland compatibility layer, Xwayland. The function __glXDisp_ChangeDrawableAttributes() processes client-supplied GLX protocol requests but performs an incorrect size validation, failing to bound the read against the actual request buffer length. This is a textbook CWE-125 (Out-of-bounds Read) - client-controlled data determines how many bytes are read, allowing reads past the allocated request buffer into adjacent memory. The secondary write path in the same code block would represent a more severe CWE-787 (Out-of-bounds Write), but it is only reachable when byte-swapped client connections are active, a non-default mode. Affected products per CPE data span the xorg/xserver upstream codebase as packaged in Red Hat Enterprise Linux versions 6 through 10.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (redhat) PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
SUSE MEDIUM
Red Hat 5.5 MEDIUM

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

DescriptionCVE.org

An out-of-bounds read flaw was found in the X.Org X server and Xwayland in __glXDisp_ChangeDrawableAttributes(). A wrong size validation check can read a client-controlled number of bytes, exceeding the request buffer, leading to information disclosure. A write path also exists but requires byte-swapped clients which is disabled by default.

Threat Intelligence Overview

EPSS Score
0.0%
Top 98% exploitable
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment MSRC Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)CVE.org

cpe:2.3:a:red_hat:red_hat_enterprise_linux_10:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_6:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_7:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_8:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_8:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_9:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_9:*:*:*:*:*:*:*:*
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CVE-2026-5121 HIGH
7.5 Mar 30

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 Affected
SUSE Linux Enterprise Module for Development Tools 15 SP7 Affected

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-50262 ADVISORY https://vuldb.com/vuln/368918 REF https://access.redhat.com/errata/RHSA-2026:26562 REF https://access.redhat.com/errata/RHSA-2026:26566 REF https://access.redhat.com/errata/RHSA-2026:26590 REF https://access.redhat.com/errata/RHSA-2026:26610 REF https://access.redhat.com/errata/RHSA-2026:26709 REF https://access.redhat.com/errata/RHSA-2026:28923 REF https://access.redhat.com/errata/RHSA-2026:29844 REF https://access.redhat.com/errata/RHSA-2026:36083 REF https://access.redhat.com/errata/RHSA-2026:36085 REF https://access.redhat.com/errata/RHSA-2026:36086 REF https://access.redhat.com/errata/RHSA-2026:36087 REF https://access.redhat.com/errata/RHSA-2026:36632 REF https://access.redhat.com/errata/RHSA-2026:36633 REF https://access.redhat.com/errata/RHSA-2026:36634 REF https://access.redhat.com/errata/RHSA-2026:36768 REF https://access.redhat.com/errata/RHSA-2026:36791 REF https://access.redhat.com/errata/RHSA-2026:36792 REF https://access.redhat.com/errata/RHSA-2026:36798 REF https://access.redhat.com/errata/RHSA-2026:38502 REF https://access.redhat.com/errata/RHSA-2026:38810 REF https://access.redhat.com/errata/RHSA-2026:46377 REF https://access.redhat.com/errata/RHSA-2026:46382 REF https://access.redhat.com/errata/RHSA-2026:46385 REF https://access.redhat.com/errata/RHSA-2026:46392 REF https://access.redhat.com/errata/RHSA-2026:46456 REF https://access.redhat.com/errata/RHSA-2026:46460 REF https://access.redhat.com/errata/RHSA-2026:46473 REF https://access.redhat.com/errata/RHSA-2026:49519 REF https://access.redhat.com/security/cve/CVE-2026-50262 REF https://bugzilla.redhat.com/show_bug.cgi?id=2485387 REF https://gitlab.freedesktop.org/xorg/xserver/-/commit/6d459e4daf715bea8abdafa8fb130be2f8a1d145 REF https://lists.x.org/archives/xorg-announce/2026-June/003702.html REF https://redhat.atlassian.net/browse/PSIRTSUPT-16950

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