Joomla RSFiles! (com_rsfiles) unauthenticated file-upload RCE (CVSS 4.0 10.0); part of the mySites.guru Joomla-extension CWE-434 wave

Joomla file-upload RCE wave adds RSFiles! (CVE-2026-57827, unauth, CVSS 10.0) and Phoca Download (CVE-2026-57828, CVSS 9.0)

Two more third-party Joomla extensions have patched unrestricted-file-upload flaws that end in remote code execution, both disclosed and fixed on 2026-07-10 by the same researcher (Phil Taylor of mySites.guru) whose source-code audits have been driving an ongoing wave of the identical CWE-434 bug class across the Joomla extension ecosystem. In RSFiles! (com_rsfiles) through 1.17.11, the permission gate and file-type allow-list live in a pre-flight method while the method that actually writes the upload to disk performs no permission check and no extension check; because that write method can be called directly with no site-wide CSRF token and no access check, an anonymous visitor bypasses the gate entirely, and RSFiles!'s default downloads folder sits inside the web root with PHP execution enabled (the protective .htaccess is an opt-in setting that is off by default), so a .php upload lands in a directory that executes it, giving unauthenticated RCE (CVE-2026-57827, CVSS 4.0 10.0) (mySites.guru, 2026-07-10). The vendor RSJoomla! shipped 1.17.12 the same day, "update NOW!". In Phoca Download (com_phocadownload) through 6.1.2, the non-default frontend member-upload feature runs under a different internal upload mode than the one the allow-list check was written for, so the configured file-type restriction is never consulted and a registered member can upload and execute a .php file into the public user-upload folder; authenticated RCE that requires an account plus the member-upload feature enabled (CVE-2026-57828, CVSS 4.0 9.0, fixed in 6.1.3) (mySites.guru, 2026-07-10).

Neither flaw has a published proof-of-concept and neither is confirmed exploited yet, but the wave's earlier members have a short track record from disclosure to in-the-wild abuse: JoomShaper SP Page Builder, Joomlack Page Builder CK, Balbooa Forms and iCagenda all carry the same unauthenticated-or-low-auth file-upload primitive (mySites.guru, 2026-07-10). All four were exploited, and CISA added them to its KEV catalog within days: CVE-2026-48908 (SP Page Builder) and CVE-2026-56290 (Page Builder CK) on 2026-07-07, CVE-2026-48939 (iCagenda) and CVE-2026-56291 (Balbooa Forms) on 2026-07-10 (CISA KEV). Joomla is heavily used across Swiss and European municipal and public-sector websites, and extension-level exposure is independent of core-Joomla patch status, so an otherwise up-to-date site can still be exposed through either component.