https://feed.craftedsignal.io/tags/arbitrary-file-upload/Trending threats, MITRE ATT&CK coverage, and detection metadata — refreshed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioSat, 02 May 2026 10:16:18 +0000https://feed.craftedsignal.io/briefs/2026-05-sunnet-file-upload/Sat, 02 May 2026 10:16:18 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-05-sunnet-file-upload/A privileged remote attacker can exploit CVE-2026-7490 in Sunnet CTMS and CPAS to upload and execute web shell backdoors, leading to arbitrary code execution on the server.CVE-2026-7490 is an arbitrary file upload vulnerability found in Sunnet CTMS and CPAS. Disclosed in May 2026, this vulnerability enables a privileged attacker to upload malicious files, specifically web shell backdoors, to the affected server. This can be achieved remotely, without requiring local system access, given the attacker already possesses valid privileged credentials for the application. Successful exploitation allows the attacker to execute arbitrary code on the server, potentially leading to complete system compromise. This vulnerability poses a significant threat to organizations using these Sunnet products, as it could result in data breaches, service disruption, and other malicious activities.

Attack Chain

1. Attacker gains privileged access to the CTMS or CPAS application, either through credential theft, phishing, or other means.
2. Attacker identifies the file upload functionality within the application.
3. Attacker crafts a malicious file, such as a PHP web shell, designed to execute arbitrary commands on the server.
4. Attacker bypasses any client-side file type validation mechanisms.
5. Attacker uploads the malicious file to the server through the vulnerable file upload endpoint.
6. The application saves the file to a publicly accessible directory without proper sanitization or validation.
7. Attacker accesses the uploaded web shell via a web browser.
8. Attacker uses the web shell to execute arbitrary commands on the server, leading to full system compromise.

Impact

Successful exploitation of CVE-2026-7490 allows attackers to execute arbitrary code on the affected server. This can lead to a range of malicious activities, including data theft, modification, or destruction, installation of malware, and complete system takeover. Since the vulnerability affects CTMS and CPAS, organizations in sectors utilizing these systems for content or process management are particularly at risk. The vulnerability’s high severity allows attackers to quickly gain a foothold and potentially compromise sensitive information or disrupt business operations.

Recommendation

• Apply available patches or updates from Sunnet to address CVE-2026-7490.
• Implement the Sigma rule Detect Malicious File Uploads to Web Servers to detect suspicious file uploads based on file extensions and content.
• Review and harden file upload functionalities within CTMS and CPAS to prevent arbitrary file uploads.
• Monitor web server logs for access to suspicious files in upload directories, using the Web Shell Access Sigma rule.
• Restrict access to file upload functionalities to only authorized users with appropriate privileges.

]]>highadvisoryarbitrary-file-uploadweb-shellcode-executionhttps://feed.craftedsignal.io/briefs/2024-01-02-livewire-markdown-editor-upload/Tue, 02 Jan 2024 12:00:00 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2024-01-02-livewire-markdown-editor-upload/The livewire-markdown-editor versions before v1.3 contain an arbitrary file upload vulnerability in the MarkdownEditor::updatedAttachments() Livewire handler, allowing authenticated users to upload any file type, potentially leading to stored XSS, phishing, malware distribution, and markdown injection.Versions of mckenziearts/livewire-markdown-editor prior to v1.3 are vulnerable to arbitrary file upload via the MarkdownEditor::updatedAttachments() Livewire handler. This handler lacks server-side validation for file types, extensions, and content. An authenticated user with access to a page embedding the markdown editor can upload malicious files (e.g., .html, .svg, .js) to the disk configured by livewire-markdown-editor.disk. If this disk is a public cloud storage bucket (S3, DigitalOcean Spaces, Cloudflare R2, Scaleway Object Storage), the uploaded files are publicly accessible with a guessed Content-Type header. This vulnerability allows attackers to perform stored XSS, host phishing pages, distribute malware, and inject malicious markdown. A real-world exploitation was observed in production.

Attack Chain

1. An attacker gains access to an application using a vulnerable version of mckenziearts/livewire-markdown-editor.
2. The attacker navigates to a page embedding the <livewire:markdown-editor> component.
3. The attacker uses the file upload functionality of the editor to upload a malicious file, such as a .html or .svg file containing XSS payloads.
4. The MarkdownEditor::updatedAttachments() Livewire handler processes the uploaded file without proper validation.
5. The handler stores the file on the disk configured by livewire-markdown-editor.disk (e.g., a public cloud bucket like S3, DigitalOcean Spaces, Cloudflare R2, Scaleway Object Storage).
6. The uploaded file becomes publicly accessible on the storage domain.
7. A user visits the URL of the uploaded malicious file, triggering the XSS payload or accessing the phishing page.
8. The attacker achieves their objective, such as stealing user credentials, redirecting users to malicious websites, or compromising the application’s integrity.

Impact

Successful exploitation of this vulnerability can lead to several critical impacts. Stored XSS on the storage domain can allow attackers to steal user credentials or perform other malicious actions in the context of the application. Phishing pages hosted on the application’s storage domain can trick users into revealing sensitive information. Malware distribution from a domain users trust can lead to widespread infections. Additionally, markdown injection via crafted filenames can compromise the integrity of the editor’s output. A real-world exploitation of this vulnerability was observed in production on a community platform using this package.

Recommendation

• Upgrade to mckenziearts/livewire-markdown-editor v1.3 or later to patch the vulnerability.
• If immediate upgrading is not feasible, disable the upload UI on every instance of the editor by passing :show-upload="false". This prevents the vulnerable code path from being reached.
• Monitor web server logs (category webserver, product linux) for requests to the storage domain for unusual file extensions like .html, .svg, .js, .php, or .exe, which could indicate attempted exploitation.
• Implement the file upload detection rule to identify potentially malicious file uploads to the storage domain.

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