CVE-2026-32853
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.
Does this matter?
Lower severity and a low EPSS score (0.44%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 4.0
- 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.44% probability · 37th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- libvncserver project/libvncserver
- Source
- disclosure@vulncheck.com
References
- https://github.com/LibVNC/libvncserver/commit/009008e2f4d5a54dd71f422070df3af7b3dbc931Patch
- https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcjVendor Advisory
- https://www.vulncheck.com/advisories/libvncserver-ultrazip-encoding-heap-out-of-bounds-readExploit, Vendor Advisory
- https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcjVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.