{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/products/yafnet.core--3.2.11/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["YAFNET.Core (\u003e= 4.0.0-beta01, \u003c= 4.0.4)","YAFNET.Core (\u003c= 3.2.11)"],"_cs_severities":["high"],"_cs_tags":["xss","stored-xss","web-application","yafnet"],"_cs_type":"advisory","_cs_vendors":["YAFNET"],"content_html":"\u003cp\u003eYAFNET.Core, a forum software package, is vulnerable to stored cross-site scripting (XSS). The vulnerability exists in versions 4.0.0-beta01 through 4.0.4 and up to 3.2.11. An attacker with a standard forum account can inject malicious JavaScript code into a forum post or reply. This payload is then stored server-side and rendered in the browsers of all users who view the affected post, leading to potential compromise. The injected JavaScript executes within the security context of the user viewing the thread, granting the attacker the ability to steal cookies, perform actions on behalf of the user, or redirect them to malicious sites.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker logs into the YAFNET forum with a standard user account.\u003c/li\u003e\n\u003cli\u003eAttacker navigates to a forum thread where posting is permitted.\u003c/li\u003e\n\u003cli\u003eAttacker crafts a malicious payload, such as \u003ccode\u003e\u0026quot;\u0026gt;\u0026lt;img src=x onerror=prompt(0)\u0026gt;\u003c/code\u003e, designed to inject JavaScript.\u003c/li\u003e\n\u003cli\u003eAttacker submits the post or reply containing the XSS payload.\u003c/li\u003e\n\u003cli\u003eThe YAFNET server stores the malicious payload in the database without proper sanitization or encoding.\u003c/li\u003e\n\u003cli\u003eA victim user (e.g., an administrator or another forum user) navigates to the thread containing the attacker\u0026rsquo;s post.\u003c/li\u003e\n\u003cli\u003eThe YAFNET server retrieves the malicious post from the database and renders it in the victim\u0026rsquo;s browser.\u003c/li\u003e\n\u003cli\u003eThe injected JavaScript executes in the victim\u0026rsquo;s browser, triggering the \u003ccode\u003eonerror\u003c/code\u003e event of the \u003ccode\u003e\u0026lt;img\u0026gt;\u003c/code\u003e tag and displaying a prompt, or potentially performing other malicious actions like cookie theft or redirection.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this vulnerability allows an attacker to execute arbitrary JavaScript in the browser of any user viewing the affected thread. This can lead to a variety of malicious outcomes, including session theft and account takeover (especially if the victim is an administrator), credential phishing via injected login forms, forum defacement, cryptominer injection, or malware delivery. The high likelihood of exploitation, combined with the potential for widespread impact across the entire forum user base, makes this a critical vulnerability.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade YAFNET.Core to a patched version beyond 4.0.4 or later than 3.2.11 to remediate CVE-2026-43939.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect YAFNET XSS Payload in HTTP POST Request\u0026rdquo; to detect attempts to inject XSS payloads into forum posts.\u003c/li\u003e\n\u003cli\u003eImplement robust input validation and contextual output encoding to prevent stored XSS vulnerabilities in future YAFNET deployments.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for suspicious HTTP requests containing potentially malicious JavaScript code, as described in the rule\u0026rsquo;s description.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-02T12:00:00Z","date_published":"2024-01-02T12:00:00Z","id":"/briefs/2024-01-yafnet-xss/","summary":"A stored XSS vulnerability in YAFNET.Core allows an attacker to inject arbitrary JavaScript into forum posts, which executes in the browsers of other users viewing the thread, potentially leading to account compromise and malware delivery.","title":"YAFNET Stored XSS Vulnerability in Forum Posts","url":"https://feed.craftedsignal.io/briefs/2024-01-yafnet-xss/"}],"language":"en","title":"CraftedSignal Threat Feed — YAFNET.Core (\u003c= 3.2.11)","version":"https://jsonfeed.org/version/1.1"}