{"id":"CVE-2026-42859","aliases":["DEBIAN-CVE-2026-42859","EUVD-2026-29167","GHSA-567c-gpv8-qh9h","UBUNTU-CVE-2026-42859"],"status":"published","title":"Neat VNC: Buffer overflow due to oversized RSA public keys","description":"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.","severity":{"version":"4.0","score":8.1,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00631,"percentile":0.50528,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-120"],"published":"2026-05-11T17:36:08Z","modified":"2026-10-28T11:13:31Z","fixes":[{"ecosystem":"Debian:14","package":"neatvnc","fixed_in":["0.9.1+dfsg-1.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.5.4+dfsg-1","0.5.4+dfsg-2~exp1","0.6.0+dfsg-1","0.6.0+dfsg-2","0.6.0+dfsg-3","0.6.0+dfsg-4","0.7.0+dfsg-1","0.7.0+dfsg-1~exp1","0.7.1+dfsg-1","0.7.1+dfsg-2","0.8.0+dfsg-1","0.8.0+dfsg-2","0.8.0+dfsg-3","0.9.1+dfsg-1","0.9.1+dfsg-1.1","1.0.0+dfsg-1~exp1","1.0.1+dfsg-1"]},{"source":"osv","ecosystem":"Debian:13","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1+dfsg-1","0.9.1+dfsg-1.1","1.0.0+dfsg-1~exp1","1.0.1+dfsg-1"]},{"source":"osv","ecosystem":"Debian:14","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.9.1+dfsg-1.1"}]}],"versions":["0.9.1+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.4.0+dfsg-2"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"neatvnc","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"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1+dfsg-1build1","0.9.1+dfsg-1.1","1.0.1+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"neatvnc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.9.1+dfsg-1","0.9.1+dfsg-1build1"]}],"products":[{"vendor":"any1","product":"neatvnc"}],"references":[{"url":"https://github.com/any1/neatvnc/security/advisories/GHSA-567c-gpv8-qh9h","tags":["x_refsource_CONFIRM","advisory","report"]},{"url":"https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337","tags":["x_refsource_MISC","fix","report"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42859.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42859","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-42859","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-42859","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-42859","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-42859","title":"Neat VNC: Buffer overflow due to oversized RSA public keys","description":"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.","status":"published","published":"2026-05-11T17:36:08.143Z","modified":"2026-05-11T18:22:03.144Z","cvss":[{"version":"4.0","score":8.1,"vector":"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","level":"high","assessor":"cna"}],"cwes":["CWE-120"],"updated_at":"2026-11-02T13:40:35.004553Z"}],"euvd":[{"id":"EUVD-2026-29167","description":"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.","status":"published","published":"2026-05-11T17:36:08Z","modified":"2026-05-11T18:22:03Z","cvss":[{"version":"4.0","score":8.1,"vector":"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","level":"high"}],"updated_at":"2026-11-02T19:05:10.375554Z"}],"nvd":[{"id":"CVE-2026-42859","description":"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.","status":"published","published":"2026-05-11T18:16:36.4Z","modified":"2026-10-26T18:10:00.173Z","cvss":[{"version":"4.0","score":8.1,"vector":"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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-120"],"updated_at":"2026-11-02T14:12:18.239974Z"}],"osv":[{"id":"CVE-2026-42859","title":"Neat VNC: Buffer overflow due to oversized RSA public keys","description":"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.","status":"published","published":"2026-05-11T17:36:08.143Z","modified":"2026-10-28T11:13:31.804016776Z","cvss":[{"version":"4.0","score":8.1,"vector":"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","level":"high"}],"cwes":["CWE-120"],"updated_at":"2026-11-02T15:45:04.117819Z"},{"id":"DEBIAN-CVE-2026-42859","description":"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.","status":"published","published":"2026-05-11T18:16:36.4Z","modified":"2026-10-27T09:47:36.137831857Z","cvss":[{"version":"4.0","score":8.1,"vector":"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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-02T15:45:55.251751Z"},{"id":"UBUNTU-CVE-2026-42859","description":"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.","status":"published","published":"2026-05-11T18:16:00Z","modified":"2026-10-17T12:58:16.225715144Z","cvss":[{"version":"4.0","score":8.1,"vector":"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","level":"high"}],"updated_at":"2026-11-02T16:56:18.393417Z"}]}}