{"id":49338,"date":"2026-04-25T11:35:07","date_gmt":"2026-04-25T11:35:07","guid":{"rendered":"http:\/\/localhost\/?p=49338"},"modified":"2026-04-25T11:35:07","modified_gmt":"2026-04-25T11:35:07","slug":"cesanta-mongoose-tcp-option-netbuiltinc-handleopt-infinite-loop","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=49338","title":{"rendered":"Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop_CVE-2026-6985"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;A weakness has been identified in Cesanta Mongoose up to 7.20. This vulnerability affects the function handle_opt of the file \/src\/net_builtin.c of the component TCP Option Handler. This manipulation of the argument optlen causes infinite loop. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 7.21 is able to resolve this issue. Upgrading the affected component is advised. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.&#8221;,&#8221;published&#8221;:&#8221;2026-04-25T16:15:13.639Z&#8221;,&#8221;modified&#8221;:&#8221;2026-04-25T16:15:13.639Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop&#8221;,&#8221;source&#8221;:&#8221;VulDB&#8221;,&#8221;references&#8221;:&#8221;https:\/\/vuldb.com\/vuln\/359528\\nhttps:\/\/vuldb.com\/vuln\/359528\/cti\\nhttps:\/\/vuldb.com\/submit\/796230\\nhttps:\/\/github.com\/dwBruijn\/CVEs\/blob\/main\/Mongoose\/TCP_opt_dos.md\\nhttps:\/\/github.com\/cesanta\/mongoose\/releases\/tag\/7.21&#8243;,&#8221;id&#8221;:&#8221;CVE-2026-6985&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-835&#8243;,&#8221;CWE-404&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;Cesanta Mongoose 7.0\\nCesanta Mongoose 7.1\\nCesanta Mongoose 7.2\\nCesanta Mongoose 7.3\\nCesanta Mongoose 7.4\\nCesanta Mongoose 7.5\\nCesanta Mongoose 7.6\\nCesanta Mongoose 7.7\\nCesanta Mongoose 7.8\\nCesanta Mongoose 7.9\\nCesanta Mongoose 7.10\\nCesanta Mongoose 7.11\\nCesanta Mongoose 7.12\\nCesanta Mongoose 7.13\\nCesanta Mongoose 7.14\\nCesanta Mongoose 7.15\\nCesanta Mongoose 7.16\\nCesanta Mongoose 7.17\\nCesanta Mongoose 7.18\\nCesanta Mongoose 7.19\\nCesanta Mongoose 7.20&#8243;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:6.9,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:4.0\/AV:N\/AC:L\/AT:N\/PR:N\/UI:N\/VC:N\/VI:N\/VA:L\/SC:N\/SI:N\/SA:N\/E:P&#8221;,&#8221;version&#8221;:&#8221;4.0&#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;Mongoose&#8221;,&#8221;version&#8221;:&#8221;7.0&#8243;,&#8221;vendor&#8221;:&#8221;Cesanta&#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;A weakness has been identified in Cesanta Mongoose up to 7.20. This vulnerability affects the function handle_opt of the file \/src\/net_builtin.c of the component TCP&#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":[6,8,48,12,21,13,7,11,5],"class_list":["post-49338","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-69","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>Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop_CVE-2026-6985 - 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=49338\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop_CVE-2026-6985 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;A weakness has been identified in Cesanta Mongoose up to 7.20. 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