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CVE Record

CVE-2026-34001: Xorg: xwayland: x.org x server: use-after-free vulnerability leads to server crash and potential memory corruption

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-34001 is a high-severity flaw in X.Org X server components used by Red Hat systems. A user who can access the X11 server could crash the graphical session and may trigger memory corruption. The source bundle does not show public active exploitation.

Executive priority

Treat this as a high-priority Linux desktop and remote-GUI patching issue, not an internet-wide emergency. Focus remediation on systems where multiple users or remote GUI access increase the chance of hostile local access.

Technical view

The flaw is a use-after-free in XSYNC fence triggering, specifically miSyncTriggerFence(). The bundle lists affected Red Hat xorg-x11-server, xorg-x11-server-Xwayland, and tigervnc packages across RHEL 6 ELS, 7 ELS, 8 variants, and 10 streams. CVSS is 7.8 with local, low-complexity, low-privilege, no-user-interaction characteristics.

Likely exposure

Exposure is most relevant on Red Hat systems running affected Xorg, Xwayland, or TigerVNC packages, especially shared Linux desktops, VDI, remote GUI, and systems where less-trusted users can start or interact with graphical sessions.

Exploitation context

The bundle says an attacker needs access to the X11 server and no user interaction. It supports denial of service and possible memory corruption. KEV is false, and no supplied source confirms active exploitation or a public exploit.

Researcher notes

Evidence supports a local, authenticated attack path through XSYNC fence handling. The main uncertainty is exploitability beyond denial of service: memory corruption is possible, but the bundle does not prove code execution, public exploit availability, or active exploitation.

Mitigation direction

  • Review the linked Red Hat advisories for corrected package guidance.
  • Update affected xorg-x11-server, Xwayland, and tigervnc packages when fixes apply.
  • Prioritize shared desktops, VDI, and remote GUI hosts first.
  • Restrict X11 server access to trusted users where operationally feasible.
  • Monitor vendor advisories because fixed versions are not fully detailed in the bundle.

Validation and detection

  • Inventory installed Red Hat xorg-x11-server, Xwayland, and tigervnc packages.
  • Compare package versions and RHEL streams against the affected list.
  • Identify systems exposing shared or remote graphical sessions.
  • Confirm Red Hat errata applicability for each lifecycle stream.
  • Review crash telemetry for repeated X server or TigerVNC failures.
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-825: 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-2026-34001 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
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

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.

2CVSS vectors
7Timeline events
2ADP providers
39Source links

SSVC decision data

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

CVSS vector scores

2 official scores

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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9redhat
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-34001Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. Source timelineredhat

    Reported to Red Hat.

  4. ADP timelineredhat-SADP

    Made public.

  5. Source timelineredhat

    Made public.

  6. CVE publishedCVE Program

    The CVE record was published.

  7. CVE updatedCVE Program

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPxorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption
other:Red Hat severity ratingcvssV3_1
  • 2026-03-25T07:00:05.329Z: Reported to Red Hat.
  • 2026-04-23T14:14:42.224Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Red HatRed Hat Enterprise Linux 10xorg-x11-server-Xwayland, 0:24.1.5-6.el10_1affected
Red HatRed Hat Enterprise Linux 10xorg-x11-server-Xwayland, 0:24.1.9-4.el10_2affected
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 8xorg-x11-server-Xwayland, 0:21.1.3-20.el8_10affected
Red HatRed Hat Enterprise Linux 8xorg-x11-server, 0:1.20.11-28.el8_10affected
Red HatRed Hat Enterprise Linux 8tigervnc, 0:1.15.0-9.el8_10affected
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 Advanced Mission Critical Update Supporttigervnc, 0:1.12.0-6.el8_6.17affected
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Ontigervnc, 0:1.12.0-6.el8_6.17affected
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 9tigervnc, 0:1.15.0-6.el9_7.1affected
Red HatRed Hat Enterprise Linux 9xorg-x11-server-Xwayland, 0:23.2.7-6.el9_7affected
Red HatRed Hat Enterprise Linux 9xorg-x11-server, 0:1.20.11-33.el9_7affected
Weakness

CWE details

CWE-825

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

CWE-825 · source CWE mapping

Expired Pointer Dereference

Expired Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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