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CVE-2026-44988

LibVNCClient Tight Gradient decoding allows malicious server-triggered heap/stack OOB writes PUBLISHED

Description (CNA)

LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.

Affected (CNA)

Vendor / productVersions
LibVNC / libvncserveraffected <= 0.9.15

CWE

CWE-787

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.