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CVE Record

CVE-2026-34002: Xorg: xwayland: x.org x server: information disclosure or denial of service via out-of-bounds read in xkb modifier map handling

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.

MediumCVSS 6.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-34002 affects X.Org X server handling of keyboard modifier maps. A user or process that already has access to the X11 server could trigger an out-of-bounds read, potentially exposing sensitive memory or crashing the graphical session/server. Business urgency is moderate because exploitation requires local/X11 access, but impact can include confidentiality loss and denial of service.

Executive priority

Schedule remediation in the normal security patch cycle, with faster action for shared Linux desktops, VNC infrastructure, and systems handling sensitive graphical sessions. This is not confirmed actively exploited, but confidentiality impact is rated high in CVSS and affected packages are common in enterprise Linux environments.

Technical view

The flaw is an out-of-bounds read in XKB modifier map handling in X.Org X server/Xwayland-related components. Red Hat lists affected xorg-x11-server, xorg-x11-server-Xwayland, and tigervnc packages across specified RHEL 6 ELS, 7 ELS, 8.x extended support streams, and RHEL 10 EUS. CVSS 3.1 is 6.1: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L.

Likely exposure

Exposure is most relevant on Red Hat systems running affected X.Org, Xwayland, or TigerVNC packages where untrusted or lower-privileged users can access the X11 server. Headless servers without these packages or without reachable X11/VNC services are less likely exposed, but package and service inventory is needed.

Exploitation context

The source bundle states an attacker needs access to the X11 server and can send a malformed request. The issue is not listed as CISA KEV in the provided data, and no cited source states active exploitation. Treat this as a local/session-bound risk, not confirmed internet-wide exploitation.

Researcher notes

Key constraints are attacker access to the X11 server and malformed XKB modifier map handling. The bundle identifies CWE-805 and Red Hat-affected package streams, but does not include upstream commit details, proof of concept, or non-Red Hat impact. Avoid assuming exploitability beyond the stated local/X11-access model.

Mitigation direction

  • Apply the applicable Red Hat RHSA update for the affected product stream.
  • Prioritize systems with shared desktops, VNC, kiosks, or multi-user graphical environments.
  • Restrict X11 and VNC access to trusted users and networks.
  • If patching is delayed, reduce or disable unnecessary graphical/X11 exposure.
  • Monitor Red Hat advisories for updated package guidance.

Validation and detection

  • Inventory xorg-x11-server, xorg-x11-server-Xwayland, and tigervnc package versions.
  • Map systems to the affected RHEL support streams listed in the CVE data.
  • Confirm the relevant RHSA advisory has been applied successfully.
  • Verify X11/VNC access is limited to authorized users.
  • Review logs for unexpected X server or graphical session crashes.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-805: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-34002 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
5Timeline events
1ADP providers
26Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6.1CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L1.84.2redhat

Vulnerability scoring details

Base CVSS 3.1 score

6.1Medium
CVSS 3.1 vector shape for CVE-2026-34002Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. Source timelineredhat

    Reported to Red Hat.

  3. Source timelineredhat

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Red HatRed Hat Enterprise Linux 10.0 Extended Update Supportxorg-x11-server-Xwayland, 0:24.1.5-6.el10_0affected
Red HatRed Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONtigervnc, 0:1.1.0-25.el6_10.16affected
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Supportxorg-x11-server, 0:1.20.4-34.el7_9affected
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Supporttigervnc, 0:1.8.0-36.el7_9.4affected
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportxorg-x11-server, 0:1.20.10-4.el8_4affected
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supporttigervnc, 0:1.11.0-8.el8_4.15affected
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onxorg-x11-server, 0:1.20.10-4.el8_4affected
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Ontigervnc, 0:1.11.0-8.el8_4.15affected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportxorg-x11-server-Xwayland, 0:21.1.3-2.el8_6.6affected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportxorg-x11-server, 0:1.20.11-7.el8_6affected
Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update Servicexorg-x11-server-Xwayland, 0:21.1.3-2.el8_6.6affected
Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update Servicexorg-x11-server, 0:1.20.11-7.el8_6affected
Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP Solutionsxorg-x11-server-Xwayland, 0:21.1.3-2.el8_6.6affected
Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP Solutionsxorg-x11-server, 0:1.20.11-7.el8_6affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Servicexorg-x11-server-Xwayland, 0:21.1.3-13.el8_8affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Servicexorg-x11-server, 0:1.20.11-18.el8_8affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Servicetigervnc, 0:1.12.0-15.el8_8.17affected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionsxorg-x11-server-Xwayland, 0:21.1.3-13.el8_8affected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionsxorg-x11-server, 0:1.20.11-18.el8_8affected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionstigervnc, 0:1.12.0-15.el8_8.17affected
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutionsxorg-x11-server-Xwayland, 0:21.1.3-5.el9_0affected
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutionsxorg-x11-server, 0:1.20.11-13.el9_0affected
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutionstigervnc, 0:1.11.0-22.el9_0.17affected
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutionsxorg-x11-server-Xwayland, 0:21.1.3-10.el9_2affected
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutionsxorg-x11-server, 0:1.20.11-20.el9_2affected
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutionstigervnc, 0:1.12.0-14.el9_2.14affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supportxorg-x11-server, 0:1.20.11-28.el9_4affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supportxorg-x11-server-Xwayland, 0:22.1.9-8.el9_4affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supporttigervnc, 0:1.13.1-8.el9_4.9affected
Red HatRed Hat Enterprise Linux 9.6 Extended Update Supportxorg-x11-server, 0:1.20.11-33.el9_6affected
Weakness

CWE details

CWE-805

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-805 · source CWE mapping

Buffer Access with Incorrect Length Value

Buffer Access with Incorrect Length Value represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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