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Description

LibVNCServer versions 0.9.15 and prior (fixed in commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.

PUBLISHED Reserved 2026-03-16 | Published 2026-03-24 | Updated 2026-03-25 | Assigner VulnCheck




MEDIUM: 6.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N

Problem types

CWE-125 Out-of-bounds read

Product status

Default status
unaffected

Any version
affected

009008e2f4d5a54dd71f422070df3af7b3dbc931 (git)
unaffected

Credits

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. finder

References

github.com/...server/security/advisories/GHSA-87q7-v983-qwcj exploit

github.com/...server/security/advisories/GHSA-87q7-v983-qwcj vendor-advisory

github.com/...ommit/009008e2f4d5a54dd71f422070df3af7b3dbc931 patch

www.vulncheck.com/...trazip-encoding-heap-out-of-bounds-read third-party-advisory

cve.org (CVE-2026-32853)

nvd.nist.gov (CVE-2026-32853)

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