Tight JPEG decoding in TightVNC and UltraVNC viewers contains a heap-based buffer overflow vulnerability

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-128321
StatePUBLISHED
Assignercertcc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-13 02:18:56 UTC
Updated2026-11-13 02:18:56 UTC
DescriptionTight JPEG decoding in TightVNC and UltraVNC viewers contains a heap-based buffer overflow because an attacker-controlled framebuffer rectangle width is not validated against a fixed-size decoding buffer. A malicious VNC server can cause an out-of-bounds heap write when a user connects, resulting in application crash and potentially other memory-corruption impacts.

Risk And Classification

Problem Types: CWE-122 Heap-Based Buffer Overflow

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA UltraVNC UltraVNC affected 1.8.2.4 1.8.2.6 custom Not specified
CNA Glavsoft TightVNC TightVNC affected 1.3.10 1.3.10 custom Not specified

References

ReferenceSourceLinkTags
github.com/ultravnc/ultravnc [email protected] github.com
www.tightvnc.com [email protected] www.tightvnc.com
www.kb.cert.org/vuls/id/644655 af854a3a-2127-422b-91ae-364da2661108 www.kb.cert.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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