{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-7829: UltraVNC repeater authenticated out-of-bounds write in rule parser via oversized token","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-7829","status":"final","version":"1","initial_release_date":"2026-07-01T03:33:22.888Z","current_release_date":"2026-07-01T03:33:22.888Z","revision_history":[{"date":"2026-07-01T03:33:22.888Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy_s copies a rule token into temp1[rule1] (25-byte destination) or temp2/temp3 (16-byte destination), the code unconditionally writes a NUL terminator at temp1[rule1][len] = 0 without clamping len to the destination size. When an authenticated administrator saves a rule with a token length equal to or greater than the destination size, the NUL byte is written one or more bytes past the end of the stack-allocated array, corrupting adjacent stack data. An attacker who has obtained admin credentials (including via CVE-2026-7839 default password) can trigger this to gain code execution on the repeater host.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-7829 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-7829"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-7829"},{"category":"external","summary":"UltraVNC project page","url":"https://uvnc.com/"},{"category":"external","summary":"UltraVNC source repository","url":"https://github.com/ultravnc/UltraVNC"}]},"product_tree":{"branches":[{"category":"vendor","name":"uvnc","branches":[{"category":"product_name","name":"UltraVNC","branches":[{"category":"product_version_range","name":"<=1.8.2.2","product":{"name":"uvnc UltraVNC <=1.8.2.2","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:uvnc:ultravnc:*:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-7829","title":"UltraVNC repeater authenticated out-of-bounds write in rule parser via oversized token","notes":[{"category":"description","text":"UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy_s copies a rule token into temp1[rule1] (25-byte destination) or temp2/temp3 (16-byte destination), the code unconditionally writes a NUL terminator at temp1[rule1][len] = 0 without clamping len to the destination size. When an authenticated administrator saves a rule with a token length equal to or greater than the destination size, the NUL byte is written one or more bytes past the end of the stack-allocated array, corrupting adjacent stack data. An attacker who has obtained admin credentials (including via CVE-2026-7839 default password) can trigger this to gain code execution on the repeater host.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1"]},"scores":[{"cvss_v3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","baseScore":7.2,"baseSeverity":"HIGH"},"products":["CSAFPID-1"]}],"remediations":[{"category":"none_available","details":"No fixed version is published yet. Monitor the upstream advisory.","product_ids":["CSAFPID-1"]}]}]}