PT-2026-44004 · Unknown · Libvncclient

Yeonba0918 · Published 2026-05-27 · Updated 2026-06-05 · CVE-2026-44988

Positive Technologies (AI Summary)

CVSS v3.1

8.8

High

Base vector

AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions LibVNCClient versions prior to 0.9.16

Description The Tight encoding decoder in LibVNCClient uses fixed-size 2048-pixel scratch buffers for the Gradient filter but fails to reject Tight rectangles with a width exceeding 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a client based on LibVNCClient connects, it processes the server-controlled rectangle width and writes beyond the fixed-size Gradient buffers, leading to a buffer overflow.

Recommendations Update to version 0.9.16 or later.

Exploit

Fix

Memory Corruption

Weakness Enumeration

CWE-787

Related Identifiers

CVE-2026-44988

OESA-2026-2490

OESA-2026-2491

OESA-2026-2564

OESA-2026-2565

OPENSUSE-SU-2026:10905-1

Affected Products

Libvncclient

References · 19

• 🔥 https://github.com/LibVNC/libvncserver/security/advisories/GHSA-jcc5-8wj4-7c58 · Exploit
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-44988 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2564 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2490 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-44988 · Security Note
• https://osv.dev/vulnerability/openSUSE-SU-2026:10905-1 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2491 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-44988 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2565 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-44988 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-44988 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-44988 · Security Note
• https://github.com/LibVNC/libvncserver/commit/5b270544b85233668b98161323297d418a8f5fd1 · Note
• https://openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2491 · Note
• https://suse.com/security/cve/CVE-2026-44988 · Note