Raw vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:NSummary
CVE-2026-40909 is a high-severity Path Traversal (CWE-22) vulnerability in Wwbn Avideo. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 48th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-40909 is a path traversal vulnerability (CWE-22) in WWBN AVideo, an open source video platform, affecting versions 29.0 and prior. The issue resides in the `locale/save.php` endpoint, where line 30 directly concatenates the unsanitized `$_POST['flag']` parameter into a file path, and line 40 writes the `$_POST['code']` parameter verbatim to that path using `fwrite()`. This allows attackers to construct paths that escape the intended `locale/` directory and target arbitrary writable locations on the filesystem, enabling the creation of malicious `.php` files for remote code execution (RCE). The vulnerability carries a CVSS v3.1 score of 8.7 (AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N).
An authenticated admin user—or any attacker capable of tricking an admin into a cross-site request forgery (CSRF) interaction—can exploit this flaw. The endpoint lacks CSRF token validation, and session cookies use `SameSite=None`, facilitating CSRF attacks. By supplying a crafted `flag` value (e.g., using `../` sequences) and malicious PHP code in `code`, the attacker can write executable files to server locations like web roots, leading to full RCE on the host.
The fixing commit, 57f89ffbc27d37c9d9dd727212334846e78ac21a, addresses the issue in the WWBN/AVideo repository. GitHub Security Advisory GHSA-6rc6-p838-686f provides further details on the vulnerability and recommends upgrading to a patched version.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-24288
Vulnerability Data
WWBN AVideo is an open source video platform. In versions 29.0 and prior, the locale save endpoint (`locale/save.php`) constructs a file path by directly concatenating `$_POST['flag']` into the path at line 30 without any sanitization. The `$_POST['code']` parameter is then…
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written verbatim to that path via `fwrite()` at line 40. An admin attacker (or any user who can CSRF an admin, since no CSRF token is checked and cookies use `SameSite=None`) can traverse out of the `locale/` directory and write arbitrary `.php` files to any writable location on the filesystem, achieving Remote Code Execution. Commit 57f89ffbc27d37c9d9dd727212334846e78ac21a fixes the issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.3.2
Mitigating Controls (NIST 800-53 r5) AI
Enforces the intended directory access authorizations that path traversal would otherwise bypass.
Input validation directly neutralizes special path elements before pathname construction occurs.
Least privilege reduces the impact of any unauthorized file access obtained via traversal.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Patching/maintenance can remediate known path-traversal flaws in deployed software (partial prevention of exploitability) but does nothing to stop the coding defect from being introduced in the first place.
PR.AA-05 defines and reviews access policies but does not address code-level pathname neutralization, so neither direction prevents CWE-22.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development catches path traversal via static/dynamic analysis.
Secure SDLC mandates input validation and path sanitization that directly prevent path traversal.
Application security requirements include rules for safe file handling and canonicalization.
Secure architecture principles require least-privilege file access and directory isolation.
Secure coding standards explicitly forbid unsafe path construction and mandate safe APIs.
Information access restriction limits which files an application may read or write.