Is there a public exploit for CVE-2026-128321?

No public exploit for CVE-2026-128321 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

What does CVE-2026-128321 affect?

CVE-2026-128321 affects Glavsoft (TightVNC), UltraVNC TightVNC, UltraVNC.

— Unscored

Tight JPEG decoding in TightVNC and UltraVNC viewers contains a heap-based buffer overflow because an attacker-controlled framebuffer…

CVE-2026-128321

Tight 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.

Assessment

CVSS: Not yet scored
Severity: Unscored
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 13 November 2026
Last updated: 13 November 2026
Affected: Glavsoft (TightVNC) · UltraVNC · TightVNC · UltraVNC
Assigner: certcc

At the source

EUVD (ENISA)

References

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