{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/mantisbt--2.28.1/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["mantisbt (\u003c= 2.28.1)","mantisbt/mantisbt"],"_cs_severities":["high"],"_cs_tags":["csp-bypass","xss","attachment","mime-sniffing"],"_cs_type":"advisory","_cs_vendors":["MantisBT"],"content_html":"\u003cp\u003eMantisBT, a web-based bug tracking system, is vulnerable to a content security policy (CSP) bypass. Specifically, the vulnerability, identified as CVE-2026-40597, allows an attacker to circumvent the CSP\u0026rsquo;s \u003ccode\u003escript-src\u003c/code\u003e directive. This is achieved by uploading a specially crafted attachment to a MantisBT issue. The vulnerability exists in MantisBT versions 2.28.1 and earlier. An attacker must first inject HTML or XSS. When the attachment is accessed via the \u003ccode\u003efile_download.php\u003c/code\u003e link, PHP\u0026rsquo;s finfo mechanism incorrectly identifies it as a valid JavaScript MIME type. Because of this, the browser executes the payload within the context of the MantisBT application. This can lead to Cross-Site Scripting (XSS) attacks.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker identifies or exploits an existing XSS or HTML injection vulnerability in MantisBT.\u003c/li\u003e\n\u003cli\u003eAttacker crafts a malicious payload designed to execute JavaScript code within the browser, and ensures that it will be sniffed as JavaScript by PHP\u0026rsquo;s \u003ccode\u003efinfo\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eAttacker uploads the crafted payload as an attachment to a MantisBT issue using the standard attachment upload functionality.\u003c/li\u003e\n\u003cli\u003eMantisBT stores the attachment, associating it with the specific issue.\u003c/li\u003e\n\u003cli\u003eA user (victim) accesses the issue containing the malicious attachment.\u003c/li\u003e\n\u003cli\u003eThe user clicks the \u003ccode\u003efile_download.php\u003c/code\u003e link associated with the uploaded attachment.\u003c/li\u003e\n\u003cli\u003eThe webserver serves the attachment via \u003ccode\u003efile_download.php\u003c/code\u003e. PHP\u0026rsquo;s \u003ccode\u003efinfo\u003c/code\u003e incorrectly identifies the MIME type of the file as a valid JavaScript MIME type.\u003c/li\u003e\n\u003cli\u003eThe browser imports the attachment as a \u003ccode\u003e\u0026lt;script\u0026gt;\u003c/code\u003e tag and executes the attacker-controlled JavaScript code within the security context of the MantisBT domain, leading to XSS.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this vulnerability, in conjunction with a pre-existing XSS or HTML injection, allows an attacker to execute arbitrary JavaScript code in the context of the MantisBT application. This can lead to session hijacking, defacement of the MantisBT interface, sensitive information theft, or other malicious actions performed on behalf of the victim user. Given the wide use of MantisBT in software development and IT support organizations, a successful attack could impact a significant number of users.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade MantisBT to a patched version beyond 2.28.1 as indicated in the advisory (\u003ca href=\"https://github.com/advisories/GHSA-9c3j-xm6v-j7j3)\"\u003ehttps://github.com/advisories/GHSA-9c3j-xm6v-j7j3)\u003c/a\u003e.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eDetect MantisBT CSP Bypass via JavaScript MIME Sniffing\u003c/code\u003e to detect attempts to exploit CVE-2026-40597.\u003c/li\u003e\n\u003cli\u003eReview and harden input validation and output encoding mechanisms to prevent XSS vulnerabilities, which are a prerequisite for exploiting CVE-2026-40597.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-11T19:35:30Z","date_published":"2026-05-11T19:35:30Z","id":"https://feed.craftedsignal.io/briefs/2026-05-mantisbt-csp-bypass/","summary":"A content security policy bypass vulnerability, CVE-2026-40597, exists in MantisBT versions 2.28.1 and earlier, allowing an attacker to bypass the _script-src_ directive by uploading a crafted attachment that, when downloaded, executes as JavaScript due to MIME type sniffing, given a pre-existing XSS / HTML injection vulnerability.","title":"MantisBT Content Security Policy Bypass via Attachment Upload (CVE-2026-40597)","url":"https://feed.craftedsignal.io/briefs/2026-05-mantisbt-csp-bypass/"}],"language":"en","title":"CraftedSignal Threat Feed — Mantisbt (\u003c= 2.28.1)","version":"https://jsonfeed.org/version/1.1"}