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TI-2026-69581 Aliases CVE-2026-107614GHSA-v6fq-v4c3-2qr7

Integer underflow in TightVNC Server cursor shape trimming

Priority LOW 26CWE-125Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
Low · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

GlavSoft TightVNC Server for Windows from 0 before 2.8.88 contains an integer underflow in the cursor shape trimming routine WinCursorShapeUtils::trimTransparent(), which is classified as CWE-191. A local authenticated user can send a cursor shape with a width or height of zero on the DXGI capture path, causing the server to crash and potentially read memory beyond the 64 KB cursor buffer.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

An integer underflow in WinCursorShapeUtils::trimTransparent() in GlavSoft TightVNC Server for Windows before 2.8.88 allows a local authenticated user to crash the server, and potentially read out-of-bounds memory, by causing a cursor shape with a width or height of zero to be processed on the DXGI capture path. The loop bound width - 1 wraps to 0xFFFFFFFF, producing an access roughly 4 GB beyond the 64 KB cursor buffer; a monochrome cursor of height 1 also becomes 0 because getCursorHeight() halves the height in place.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00106 1st percentileScored 2026-11-07
Fix Fixed TightVNC (GlavSoft): 2.8.88

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
GlavSoftTightVNCbefore 2.8.882.8.88Patch availableCNA
  • TightVNC VendorGlavSoft Affected before 2.8.88 Fixed in 2.8.88 Patch available CNA

Remediation

Update TightVNC Server for Windows to version 2.8.88 or later, which fixes the flaw. The sources list no advisory identifier for this fix.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA TightVNC (GlavSoft) Fixed in 2.8.88

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    GlavSoft TightVNC 2.8.88

    5 records Highest priority Priority LOW 5 LOW

    Other records, highest priority first

    • TI-2026-69582 DLL search order hijacking via screenhooks libraries in TightVNC ServerPriority LOW 35
    • TI-2026-69579 Incorrect permissions on TightVNC IPC shared memory in TightVNC ServerPriority LOW 35
    • TI-2026-69578 Out-of-bounds read in TightVNC Viewer ZRLE palette decodingPriority LOW 31
    Show all 5 records →

Timeline

  1. 2026-10-08 Threatist record created from CVE-2026-107614
  2. 2026-10-08 Alias added: GHSA-v6fq-v4c3-2qr7

References

Patch 1

Other 1

  • TI-2026-69582 DLL search order hijacking via screenhooks libraries in TightVNC Server CVSS 3.1HIGH 7.8
  • TI-2026-69579 Incorrect permissions on TightVNC IPC shared memory in TightVNC Server CVSS 3.1HIGH 7.8
  • TI-2026-69578 Out-of-bounds read in TightVNC Viewer ZRLE palette decoding CVSS 3.1HIGH 7.1
  • TI-2026-69580 NULL pointer dereference in TightVNC Server Win8ScreenDriver crashes server CVSS 3.1MEDIUM 5.9

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences