{"id":"UBUNTU-CVE-2026-42859","details":"Neat VNC is a VNC server library. Prior to 0.9.6, a pre-authentication stack buffer overflow exists in neatvnc in the RSA-AES security type handler. An unauthenticated remote attacker who can reach the VNC listening socket can send a crafted security type 5 (RSA-AES) or security type 129 (RSA-AES-256) handshake with an oversized client RSA public key, causing rsa_aes_send_challenge in src/auth/rsa-aes.c to overflow a 1024-byte on-stack buffer when encrypting the server challenge. This results in at least a denial of service via server crash. This vulnerability is fixed in 0.9.6.","modified":"2026-05-27T19:15:22.673867211Z","published":"2026-05-11T18:16:00Z","upstream":["CVE-2026-42859"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-42859"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-42859"},{"type":"REPORT","url":"https://github.com/any1/neatvnc/security/advisories/GHSA-567c-gpv8-qh9h"},{"type":"REPORT","url":"https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337"}],"affected":[{"package":{"name":"neatvnc","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/neatvnc?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.4.0+dfsg-2"],"ecosystem_specific":{"binaries":[{"binary_name":"libneatvnc0","binary_version":"0.4.0+dfsg-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42859.json"}},{"package":{"name":"neatvnc","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/neatvnc?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.6.0+dfsg-4build1","0.7.0+dfsg-1","0.7.1+dfsg-1","0.7.1+dfsg-2","0.7.1+dfsg-2build2","0.7.1+dfsg-2build3"],"ecosystem_specific":{"binaries":[{"binary_name":"libneatvnc0","binary_version":"0.7.1+dfsg-2build3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42859.json"}},{"package":{"name":"neatvnc","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/neatvnc?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libneatvnc0","binary_version":"0.9.1+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42859.json"}},{"package":{"name":"neatvnc","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/neatvnc?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1+dfsg-1","0.9.1+dfsg-1build1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.9.1+dfsg-1build1","binary_name":"libneatvnc0"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42859.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U"},{"type":"Ubuntu","score":"medium"}]}