{"id":"CVE-2026-42859","summary":"Neat VNC: Buffer overflow due to oversized RSA public keys","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.","aliases":["GHSA-567c-gpv8-qh9h"],"modified":"2026-08-12T16:24:23.852455Z","published":"2026-05-11T17:36:08.143Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-120"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42859.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42859.json"},{"type":"ADVISORY","url":"https://github.com/any1/neatvnc/security/advisories/GHSA-567c-gpv8-qh9h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42859"},{"type":"FIX","url":"https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/any1/neatvnc","events":[{"introduced":"0"},{"fixed":"1f6cd6b75cc167fed3a19a9d1552a1f662f6b337"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"0.9.6"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v0.9.1","v0.9.0","v0.9.0-rc0","v0.8.0","v0.6.0","v0.5.1","v0.5.0","v0.4.0","v0.3.2","v0.3.1","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"vanir_signatures":[{"digest":{"function_hash":"22221566443134491447881802408760779538","length":724},"id":"CVE-2026-42859-8badf251","signature_type":"Function","signature_version":"v1","source":"https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337","target":{"file":"src/auth/rsa-aes.c","function":"on_rsa_aes_public_key"},"deprecated":false},{"signature_type":"Function","signature_version":"v1","source":"https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337","target":{"file":"src/auth/rsa-aes.c","function":"rsa_aes_send_challenge"},"deprecated":false,"digest":{"function_hash":"221587621419090949003542138390782641482","length":441},"id":"CVE-2026-42859-996ec76b"},{"digest":{"line_hashes":["239833167477462087320097054358452255718","177321285140820575147124416256834830533","6007986327389477993100476816392266200","134293002946176405258026855927400365788","317282120317357486130853329309623894184","145415935968179123210963415518803484470","263357877467086607448878692377686757482","70167750186618520029095537086431579724","201038992931910347927560822641689771166","236909668676271202885571250521573333375","316003633770106317461265877216580626379","332941537523803385594930957278154597312","7506084135956688257720752474382193937","55120906597597281891913167855566305431","226412758820377136542262339724123636231","92519627057950057525535838614847068386","2130760160407261929165302326125039847"],"threshold":0.9},"id":"CVE-2026-42859-b7996c30","signature_type":"Line","signature_version":"v1","source":"https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337","target":{"file":"src/auth/rsa-aes.c"},"deprecated":false}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42859.json","vanir_signatures_modified":"2026-08-12T16:24:23Z"}}],"schema_version":"1.9.0","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"}]}