CVE-2026-43877 Vulnerability Analysis & Exploit Details

CVE-2026-43877 Vulnerability Summary

CVE-2026-43877: WWBN AVideo is an open source video platform. In versions up to and including 29.0, objects/userSavePhoto.php is a legacy profile-photo endpoint that accepts a base64 POST parameter and writes the decoded bytes to videos/userPhoto/photo<users_id>.png. Its only access control is User::isLogged(). It does not end in .json.php, so it is excluded from the project's global autoCSRFGuard (which is suffix-scoped in objects/include_config.php). There is no CSRF token, no Origin/Referer check, and no MIME validation of the decoded bytes. Because AVideo's default cookie policy is SameSite=None; Secure on HTTPS (objects/functionsPHP.php:227), an attacker who lures a logged-in user to a malicious page can overwrite that user's profile photo with arbitrary bytes and also triggers a site-wide clearCache(true) on every forged request. Commit 9c38468041505e637101c5943c5370c68f48e3ac contains an updated fix.

CVE-2026-43877 References

External References

• https://github.com/WWBN/AVideo/commit/9c38468041505e637101c5943c5370c68f48e3ac
• https://github.com/WWBN/AVideo/security/advisories/GHSA-jw8g-5j46-44rp

CWE Common Weakness Enumeration

CAPEC Common Attack Pattern Enumeration and Classification

• JSON Hijacking (aka JavaScript Hijacking) CAPEC-111 An attacker targets a system that uses JavaScript Object Notation (JSON) as a transport mechanism between the client and the server (common in Web 2.0 systems using AJAX) to steal possibly confidential information transmitted from the server back to the client inside the JSON object by taking advantage of the loophole in the browser's Same Origin Policy that does not prohibit JavaScript from one website to be included and executed in the context of another website.
• Cross-Domain Search Timing CAPEC-462 An attacker initiates cross domain HTTP / GET requests and times the server responses. The timing of these responses may leak important information on what is happening on the server. Browser's same origin policy prevents the attacker from directly reading the server responses (in the absence of any other weaknesses), but does not prevent the attacker from timing the responses to requests that the attacker issued cross domain.
• Cross Site Identification CAPEC-467 An attacker harvests identifying information about a victim via an active session that the victim's browser has with a social networking site. A victim may have the social networking site open in one tab or perhaps is simply using the "remember me" feature to keep their session with the social networking site active. An attacker induces a payload to execute in the victim's browser that transparently to the victim initiates a request to the social networking site (e.g., via available social network site APIs) to retrieve identifying information about a victim. While some of this information may be public, the attacker is able to harvest this information in context and may use it for further attacks on the user (e.g., spear phishing).
• Cross Site Request Forgery CAPEC-62 An attacker crafts malicious web links and distributes them (via web pages, email, etc.), typically in a targeted manner, hoping to induce users to click on the link and execute the malicious action against some third-party application. If successful, the action embedded in the malicious link will be processed and accepted by the targeted application with the users' privilege level. This type of attack leverages the persistence and implicit trust placed in user session cookies by many web applications today. In such an architecture, once the user authenticates to an application and a session cookie is created on the user's system, all following transactions for that session are authenticated using that cookie including potential actions initiated by an attacker and simply "riding" the existing session cookie.

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