{"id":56086,"date":"2026-05-21T09:21:14","date_gmt":"2026-05-21T09:21:14","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=56086"},"modified":"2026-05-21T09:21:14","modified_gmt":"2026-05-21T09:21:14","slug":"select2-file-descriptor-set-overflow-causes-stack-overflow","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=56086","title":{"rendered":"select(2) file descriptor set overflow causes stack overflow_CVE-2026-39461"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available.  However, it does not verify that its socket descriptor fits within select(2)&#8217;s descriptor set size limit of FD_SETSIZE (1024).\\n\\nAn attacker able to cause an application using libcasper(3) to allocate large file descriptors, e.g., by opening many descriptors and executing a program which is not careful to close them upon startup, may trigger stack corruption.  If the target application runs with setuid root privileges, this could be used to escalate local privileges.&#8221;,&#8221;published&#8221;:&#8221;2026-05-21T09:20:26.126Z&#8221;,&#8221;modified&#8221;:&#8221;2026-05-21T12:25:47.575Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;select(2) file descriptor set overflow causes stack overflow&#8221;,&#8221;source&#8221;:&#8221;freebsd&#8221;,&#8221;references&#8221;:&#8221;https:\/\/security.freebsd.org\/advisories\/FreeBSD-SA-26:22.libcasper.asc&#8221;,&#8221;id&#8221;:&#8221;CVE-2026-39461&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-121&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;FreeBSD FreeBSD 15.0-RELEASE\\nFreeBSD FreeBSD 14.4-RELEASE\\nFreeBSD FreeBSD 14.3-RELEASE&#8221;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:5.1,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:3.1\/AV:L\/AC:L\/PR:N\/UI:N\/S:U\/C:L\/I:N\/A:L&#8221;,&#8221;version&#8221;:&#8221;3.1&#8243;},&#8221;cvss2&#8243;:{},&#8221;cvss3&#8243;:{&#8220;version&#8221;:&#8221;&#8221;,&#8221;vectorString&#8221;:&#8221;&#8221;,&#8221;baseScore&#8221;:0,&#8221;baseSeverity&#8221;:&#8221;&#8221;,&#8221;attackVector&#8221;:&#8221;&#8221;,&#8221;attackComplexity&#8221;:&#8221;&#8221;,&#8221;privilegesRequired&#8221;:&#8221;&#8221;,&#8221;userInteraction&#8221;:&#8221;&#8221;,&#8221;scope&#8221;:&#8221;&#8221;,&#8221;confidentialityImpact&#8221;:&#8221;&#8221;,&#8221;integrityImpact&#8221;:&#8221;&#8221;,&#8221;availabilityImpact&#8221;:&#8221;&#8221;,&#8221;cvssV3&#8243;:{&#8220;version&#8221;:&#8221;&#8221;,&#8221;vectorString&#8221;:&#8221;&#8221;,&#8221;baseScore&#8221;:0,&#8221;baseSeverity&#8221;:&#8221;&#8221;,&#8221;attackVector&#8221;:&#8221;&#8221;,&#8221;attackComplexity&#8221;:&#8221;&#8221;,&#8221;privilegesRequired&#8221;:&#8221;&#8221;,&#8221;userInteraction&#8221;:&#8221;&#8221;,&#8221;scope&#8221;:&#8221;&#8221;,&#8221;confidentialityImpact&#8221;:&#8221;&#8221;,&#8221;integrityImpact&#8221;:&#8221;&#8221;,&#8221;availabilityImpact&#8221;:&#8221;&#8221;}},&#8221;href&#8221;:&#8221;&#8221;,&#8221;category_name&#8221;:&#8221;CVE&#8221;,&#8221;post_link&#8221;:&#8221;&#8221;,&#8221;product&#8221;:&#8221;FreeBSD&#8221;,&#8221;version&#8221;:&#8221;15.0-RELEASE&#8221;,&#8221;vendor&#8221;:&#8221;FreeBSD&#8221;,&#8221;ai_description&#8221;:&#8221;&#8221;,&#8221;ai_severity&#8221;:&#8221;&#8221;,&#8221;ai_vendor&#8221;:&#8221;&#8221;,&#8221;ai_product&#8221;:&#8221;&#8221;,&#8221;ai_version&#8221;:&#8221;&#8221;,&#8221;ai_score&#8221;:0}<\/p>\n","protected":false},"excerpt":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available. However, it does&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[6,8,109,12,21,13,7,11,5],"class_list":["post-56086","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-51","tag-exploit","tag-medium","tag-news","tag-security","tag-tapic","tag-vulnerability"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>select(2) file descriptor set overflow causes stack overflow_CVE-2026-39461 - zero redgem<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/zero.redgem.net\/?p=56086\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"select(2) file descriptor set overflow causes stack overflow_CVE-2026-39461 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available. 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