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CVE Record

CVE-2025-26601: Xorg: xwayland: use-after-free in syncinittrigger()

A use-after-free flaw was found in X.Org and Xwayland. When changing an alarm, the values of the change mask are evaluated one after the other, changing the trigger values as requested, and eventually, SyncInitTrigger() is called. If one of the changes triggers an error, the function will return early, not adding the new sync object, possibly causing a use-after-free when the alarm eventually triggers.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2025-26601 is a memory safety flaw in X.Org and Xwayland. A local user could potentially abuse a mishandled sync alarm change to gain serious control over confidentiality, integrity, or availability on affected graphical or VNC-enabled Linux systems.

Executive priority

Patch on the normal high-severity endpoint and Linux server cycle, accelerating shared-user, administrative workstation, and remote desktop environments. There is no source-backed active exploitation signal in the bundle, but the impact rating is high across confidentiality, integrity, and availability.

Technical view

The flaw is a CWE-416 use-after-free in syncinittrigger(). If alarm change processing hits an error, a new sync object may not be added, leaving state that can be used after release when the alarm later triggers. Red Hat rates this CVSS 7.8 with local, low-complexity, low-privilege exploitation.

Likely exposure

Most relevant exposure is Linux endpoints, workstations, servers with graphical stacks, Xwayland, X.Org X server, or TigerVNC packages. The bundle identifies multiple affected Red Hat Enterprise Linux 6 ELS, 7 ELS, 8, 9, and 10 package lines.

Exploitation context

The provided CVSS vector indicates local access and low privileges are required, with no user interaction. The bundle does not show CISA KEV listing or cited active exploitation. Treat this as a high-impact local privilege or session-compromise risk, not a remotely exploitable internet-facing service issue.

Researcher notes

Evidence supports a local use-after-free in X.Org/Xwayland sync alarm handling. The exact exploitability depends on package build, session model, and memory protections. Do not assume internet exposure unless remote desktop or shared login paths provide attacker access.

Mitigation direction

  • Apply the relevant vendor security advisory updates for affected Red Hat packages.
  • Check Debian, NetApp, and other vendor guidance if those platforms are in scope.
  • Prioritize systems offering shared graphical sessions, VNC, or multi-user desktop access.
  • Restrict local shell and graphical access to trusted users until patched.

Validation and detection

  • Inventory installed xorg-x11-server, xorg-x11-server-Xwayland, and tigervnc packages.
  • Compare package versions against the affected Red Hat product entries in the bundle.
  • Verify whether systems run X.Org, Xwayland, or TigerVNC services.
  • Confirm vendor advisory updates are installed before closing remediation tickets.
Prepared
Confidence
high
Sources
11

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-416: 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-2025-26601 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.

1CVSS vectors
5Timeline events
2ADP providers
20Source links

SSVC decision data

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

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

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-26601Attack 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. 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
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Unknown vendorxserverxserver, 0, 22.0.0unaffected
Red HatRed Hat Enterprise Linux 10xorg-x11-server-Xwayland, 0:24.1.5-3.el10_0affected
Red HatRed Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONtigervnc, 0:1.1.0-25.el6_10affected
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Supporttigervnc, 0:1.8.0-36.el7_9affected
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Supportxorg-x11-server, 0:1.20.4-30.el7_9affected
Red HatRed Hat Enterprise Linux 8tigervnc, 0:1.13.1-15.el8_10affected
Red HatRed Hat Enterprise Linux 8.2 Advanced Update Supporttigervnc, 0:1.9.0-15.el8_2.13affected
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supporttigervnc, 0:1.11.0-8.el8_4.12affected
Red HatRed Hat Enterprise Linux 8.4 Telecommunications Update Servicetigervnc, 0:1.11.0-8.el8_4.12affected
Red HatRed Hat Enterprise Linux 8.4 Update Services for SAP Solutionstigervnc, 0:1.11.0-8.el8_4.12affected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supporttigervnc, 0:1.12.0-6.el8_6.13affected
Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update Servicetigervnc, 0:1.12.0-6.el8_6.13affected
Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP Solutionstigervnc, 0:1.12.0-6.el8_6.13affected
Red HatRed Hat Enterprise Linux 8.8 Extended Update Supporttigervnc, 0:1.12.0-15.el8_8.12affected
Red HatRed Hat Enterprise Linux 9tigervnc, 0:1.14.1-1.el9_5.1affected
Red HatRed Hat Enterprise Linux 9xorg-x11-server, 0:1.20.11-28.el9_6affected
Red HatRed Hat Enterprise Linux 9xorg-x11-server-Xwayland, 0:23.2.7-3.el9_6affected
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutionstigervnc, 0:1.11.0-22.el9_0.13affected
Red HatRed Hat Enterprise Linux 9.2 Extended Update Supporttigervnc, 0:1.12.0-14.el9_2.10affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supporttigervnc, 0:1.13.1-8.el9_4.5affected
Red HatRed Hat Enterprise Linux 6xorg-x11-serverunknown
Red HatRed Hat Enterprise Linux 8xorg-x11-serverunaffected
Red HatRed Hat Enterprise Linux 8xorg-x11-server-Xwaylandunaffected
Weakness

CWE details

CWE-416

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

CWE-416 · source CWE mapping

Use After Free

Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs