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Attack ChainAIDerived

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

  1. Access
    Obtain local X server session access
  2. Delivery
    Craft malformed XKB key-types request
  3. Exploit
    Trigger out-of-bounds read in XKB handler
  4. Execution
    Leak adjacent server memory or crash server
  5. Impact
    Information disclosure or denial of service

Vulnerability Assessment

Weakness
CWE
CWE-125
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.

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Exploitation Conditions

The attacker must have a local, authenticated connection to the X server (PR:L, AV:L) - i.e., an active graphical session or a process able to open the X display - and must send a crafted XKB key-types request; no user interaction is required (UI:N). Exploitation is fundamentally LIMITED by the need for local access to a running X.Org server: it cannot be triggered remotely over the network, and headless servers with no X server running are not exposed. The elevated 'higher impact' (integrity/RCE-leaning) outcomes are further gated to specific deployments - notably X servers running with root privileges - so the worst-case impact does not apply to hardened or rootless configurations.
Impact

The signals are internally consistent and point to a moderate, non-urgent priority. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H = 7.8 High) confirms this is a LOCAL vulnerability requiring an authenticated client connection to the X server, not a remote issue - no network exposure. EPSS is 0.01% (2nd percentile) and CISA SSVC records Exploitation: none and Automatable: no, though it rates Technical Impact as 'total.' No KEV listing and no known POC exist. The I:H/A:H rating from the reporter is somewhat generous for an out-of-bounds READ, which most naturally yields information disclosure and denial of service; the 'higher impact outcomes may be possible' language is the basis for the integrity claim but is conditional, so I:H should be treated as a worst-case configuration-dependent estimate rather than a confirmed write primitive. Net: a real local privilege/information-disclosure and DoS concern for multi-user or hardened desktop environments, but low likelihood of widespread opportunistic exploitation.
Exploit ScenarioDerived

A logged-in local user or a low-privilege process that already holds a connection to the X server sends a specially crafted XKB key-types request with malformed length/index fields. The server reads past the buffer bounds, leaking fragments of adjacent session memory back to the attacker or crashing, terminating the graphical session for all users. No public POC is identified, and the local attack vector with low complexity means a working exploit would be reliable but requires prior local access.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 24, 2026

Out-of-bounds memory read in the X.Org X server's XKB key types request handling allows a local, authenticated client to disclose adjacent server memory or crash the server (DoS), with higher-impact outcomes possible in certain configurations. The flaw affects the X server component shipped across Red Hat Enterprise Linux 6 through 10 and corresponding SUSE releases, and stems from missing bounds validation on an XKB request. There is no public exploit identified at time of analysis, EPSS is negligible (0.01%), and CISA/SSVC records no known exploitation.

RemediationAI

Apply your distribution's patched X.Org server packages: on Red Hat systems update per Vendor-released patch advisories RHSA-2026:10739, RHSA-2026:11352, and RHSA-2026:11369 (https://access.redhat.com/security/cve/CVE-2026-34003), and on SUSE systems apply the corresponding SUSE-SU-2026:1328-1335 / 21211 updates (e.g. https://www.suse.com/support/update/SUSE-SU-2026:1328/), then restart the display server or reboot so the running server picks up the fix. Because exploitation requires a local client connection, effective compensating controls where patching must be delayed are: restrict local/interactive login to trusted users, avoid shared multi-user X sessions, and prefer running the graphical stack under a non-root/rootless model (e.g. rootless Xorg or migrating affected hosts to Wayland where feasible) to shrink the privilege blast radius - noting the trade-off that Wayland migration can break X11-only applications and rootless mode may not be supported on all legacy RHEL 6/7 systems.

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Technical ContextAI · show details

The X.Org Server is the reference implementation of the X11 display server protocol and is the graphical backbone of most Linux desktops and workstations. The XKB (X Keyboard) extension processes keyboard-layout requests from connected clients, including the definition and lookup of 'key types.' This vulnerability is a CWE-125 out-of-bounds read: the server fails to fully validate length or index fields in an XKB key-types request before accessing the backing buffer, so a crafted request drives a read past the allocated region. Because the X server historically runs with elevated privileges and shares an address space with sensitive session state, an OOB read there can leak memory contents or corrupt server state, and the description's note about 'certain configurations' reflects that setups running the server as root or with additional privileges could escalate the impact.

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Severity by source

Vendor (redhat) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.3 HIGH

Local authenticated client (AV:L/PR:L); OOB read gives strong info disclosure (C:H) and crash (A:H), but integrity impact is only conditional, so I:L rather than I:H.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N
SUSE HIGH
Red Hat 7.8 HIGH

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
High
Availability
High

Lifecycle Timeline

2
Patch released
Apr 28, 2026 - 20:30 nvd
Patch available
CVE Published
Apr 23, 2026 - 14:54 nvd
HIGH 7.8

DescriptionCVE.org

A flaw was found in the X.Org X server's XKB key types request validation. A local attacker could send a specially crafted request to the X server, leading to an out-of-bounds memory access vulnerability. This could result in the disclosure of sensitive information or cause the server to crash, leading to a Denial of Service (DoS). In certain configurations, higher impact outcomes may be possible.

Zero Day Initiative Advisories

ZDI-26-337 X.Org Server CheckKeyTypes Buffer Overflow Privilege Escalation Vulnerability Jun 2026

Executive ViewAI

Why It Matters

X.Org X server vulnerability affecting RHEL and SUSE systems creates denial-of-service and data disclosure risk for organizations using these platforms; the vulnerability requires authenticated local access to exploit. With a HIGH severity rating, no active public exploitation, and vendor patches available, organizations should prioritize patching all affected systems within 30 days to eliminate exposure.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.0%
Top 98% exploitable
Prevalence
High
standard display server on most Linux desktop/workstation deployments
Social Media
5
Sightings
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment MSRC Vendor CIRCL 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 HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

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 MEDIUM

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

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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_6:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_7:*:*:*:*:*:*:*:*
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_8:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_9:*:*:*:*:*:*:*:*
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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Same weakness CWE-125 – Out-of-bounds Read

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CVE-2014-0160 HIGH POC
7.5
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8.8
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CVE-2017-5030 HIGH POC
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CVE-2024-48456 HIGH POC
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CVE-2024-48457 HIGH POC
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Same technique Buffer Overflow

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CVE-2015-3113 CRITICAL POC
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CVE-2011-2462 CRITICAL POC
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CVE-2020-0796 CRITICAL POC
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CVE-2019-11043 CRITICAL POC
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CVE-2009-0927 HIGH POC
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CVE-2012-1889 HIGH POC
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Vendor StatusVendor

SUSE

Severity: High
Product Status
Image SLES15-SP4-SAP Image SLES15-SP4-SAP-Azure Image SLES15-SP4-SAP-EC2 Image SLES15-SP4-SAP-GCE Image SLES15-SP4-SAPCAL Image SLES15-SP4-SAPCAL-Azure Image SLES15-SP4-SAPCAL-EC2 Image SLES15-SP4-SAPCAL-GCE Affected
Image SLES15-SP5-SAPCAL-Azure Image SLES15-SP5-SAPCAL-GCE Affected
Image SLES15-SP6-SAP Image SLES15-SP6-SAP-EC2 Image SLES15-SP6-SAPCAL Image SLES15-SP6-SAPCAL-EC2 Affected
SUSE Liberty Linux 9 Fixed
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-34003 ADVISORY https://vuldb.com/vuln/359151 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1328/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1329/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1330/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1331/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1332/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1333/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1335/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:21211/ REF https://access.redhat.com/errata/RHSA-2026:10739 REF https://access.redhat.com/errata/RHSA-2026:11352 REF https://access.redhat.com/errata/RHSA-2026:11369 REF https://access.redhat.com/errata/RHSA-2026:11388 REF https://access.redhat.com/errata/RHSA-2026:11656 REF https://access.redhat.com/errata/RHSA-2026:11692 REF https://access.redhat.com/errata/RHSA-2026:13414 REF https://access.redhat.com/errata/RHSA-2026:19125 REF https://access.redhat.com/errata/RHSA-2026:19342 REF https://access.redhat.com/errata/RHSA-2026:19343 REF https://access.redhat.com/errata/RHSA-2026:19344 REF https://access.redhat.com/errata/RHSA-2026:20547 REF https://access.redhat.com/errata/RHSA-2026:20555 REF https://access.redhat.com/errata/RHSA-2026:20557 REF https://access.redhat.com/errata/RHSA-2026:20558 REF https://access.redhat.com/errata/RHSA-2026:20560 REF https://access.redhat.com/errata/RHSA-2026:20561 REF https://access.redhat.com/errata/RHSA-2026:20562 REF https://access.redhat.com/errata/RHSA-2026:20563 REF https://access.redhat.com/errata/RHSA-2026:20575 REF https://access.redhat.com/errata/RHSA-2026:20576 REF https://access.redhat.com/errata/RHSA-2026:20590 REF https://access.redhat.com/errata/RHSA-2026:21699 REF https://access.redhat.com/errata/RHSA-2026:21712 REF https://access.redhat.com/errata/RHSA-2026:21715 REF https://access.redhat.com/errata/RHSA-2026:21716 REF https://access.redhat.com/errata/RHSA-2026:21718 REF https://access.redhat.com/errata/RHSA-2026:21741 REF https://access.redhat.com/errata/RHSA-2026:21742 REF https://access.redhat.com/errata/RHSA-2026:22424 REF https://access.redhat.com/errata/RHSA-2026:22456 REF https://access.redhat.com/errata/RHSA-2026:23254 REF https://access.redhat.com/errata/RHSA-2026:23255 REF https://access.redhat.com/errata/RHSA-2026:23496 REF https://access.redhat.com/errata/RHSA-2026:24341 REF https://access.redhat.com/security/cve/CVE-2026-34003 REF https://bugzilla.redhat.com/show_bug.cgi?id=2451113 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34003.json

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