{"id":12433,"date":"2026-09-04T18:59:24","date_gmt":"2026-09-04T10:59:24","guid":{"rendered":"https:\/\/www.54iter.cn\/?vuln=cve-2026-7840"},"modified":"2026-09-04T18:59:24","modified_gmt":"2026-09-04T10:59:24","slug":"cve-2026-7840","status":"publish","type":"vuln","link":"https:\/\/www.54iter.cn\/?vuln=cve-2026-7840","title":{"rendered":"CVE-2026-7840 [CRITICAL] &#8211; UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP a"},"content":{"rendered":"<p>UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP administration server. The functions wi_senderr() and wi_replyhdr() in repeater\/webgui\/webutils.c write the caller-supplied HTTP request URI into a fixed 1000-byte global buffer (hdrbuf) via unchecked sprintf calls. The HTTP receive buffer accepts URIs up to approximately 150 KB (WI_RXBUFSIZE = 153600), so an unauthenticated attacker who can reach the repeater HTTP port (default TCP 80) can overflow hdrbuf by at least 500 bytes with a single HTTP request containing a URI of 1500 bytes or longer, corrupting adjacent .bss-segment globals. The overflow occurs before any authentication check, making it reachable without credentials. A remote, unauthenticated attacker can achieve arbitrary code execution on the host running the repeater.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP administration server. The functions wi_senderr() and wi_replyhdr() in repeater\/webgui\/webutils.c write the cal<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-12433","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/12433","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12433"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12433"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12433"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}