{"id":37905,"date":"2026-01-28T12:56:22","date_gmt":"2026-01-28T12:56:22","guid":{"rendered":"http:\/\/localhost\/?p=37905"},"modified":"2026-01-28T12:56:22","modified_gmt":"2026-01-28T12:56:22","slug":"discourse-has-dos-vulnerability-in-username-change-endpoint","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=37905","title":{"rendered":"Discourse has DoS vulnerability in username change endpoint_CVE-2025-68659"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Discourse is an open source discussion platform. Versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 have an application level denial of service vulnerabilityin the username change functionality at try.discourse.org. The vulnerability allows attackers to cause noticeable server delays and resource exhaustion by sending large JSON payloads to the username preference endpoint PUT \/u\/\/preferences\/username, resulting in degraded performance for other users and endpoints. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. No known workarounds are available.&#8221;,&#8221;published&#8221;:&#8221;2026-01-28T18:51:40.341Z&#8221;,&#8221;modified&#8221;:&#8221;2026-01-28T18:51:40.341Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;Discourse has DoS vulnerability in username change endpoint&#8221;,&#8221;source&#8221;:&#8221;GitHub_M&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/discourse\/discourse\/security\/advisories\/GHSA-rmp6-c9rq-6q7p&#8221;,&#8221;id&#8221;:&#8221;CVE-2025-68659&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-770&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;discourse discourse \\u003c 3.5.4\\ndiscourse discourse \\u003e= 2025.11.0-latest, \\u003c 2025.11.2\\ndiscourse discourse \\u003e= 2025.12.0-latest, 2025.12.1\\ndiscourse discourse \\u003e= 2026.1.0-latest, \\u003c 2026.1.0&#8243;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:4.3,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:3.1\/AV:N\/AC:L\/PR:L\/UI:N\/S:U\/C:N\/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;discourse&#8221;,&#8221;version&#8221;:&#8221;\\u003c 3.5.4&#8243;,&#8221;vendor&#8221;:&#8221;discourse&#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;Discourse is an open source discussion platform. Versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 have an application level denial of service vulnerabilityin the username&#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":[6,8,123,12,21,13,7,11,5],"class_list":["post-37905","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-43","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>Discourse has DoS vulnerability in username change endpoint_CVE-2025-68659 - 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=37905\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Discourse has DoS vulnerability in username change endpoint_CVE-2025-68659 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Discourse is an open source discussion platform. 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