Critical Collabora Online Flaw Lets Attackers Execute Commands on Nextcloud Servers
Unauthenticated command injection CVE-2026-110447 in Nextcloud's built-in Collabora CODE Server can run commands as the web user.
Collabora Online disclosed CVE-2026-110447, an unauthenticated OS command injection (CWE-78) in proxy.php of richdocumentscode, the built-in CODE Server app for Nextcloud. A crafted network request can run commands as the web server user, but only while that built-in server is stopped, such as after a restart, upgrade, or crash. The CVSS v4 score is 9.2, and all releases before 26.4.303 are affected. Standalone Collabora Online is not affected, disabling the app is insufficient, the CVE-2025-66208 fix does not stop this issue, and no public exploitation was reported.
- CVE-2026-110447 is unauthenticated OS command injection in Nextcloud's built-in CODE Server.
- CVSS v4 score is 9.2; the built-in server must be stopped for the attack to work.
- Fixed in richdocumentscode 26.4.303; disabling the app is not sufficient.
- Standalone Collabora Online is unaffected, and the CVE-2025-66208 fix does not cover this.
- No public exploitation was reported in the advisory.
Vulnerabilities mentionedAll →
- CVE-2025-662087.21%Collabora Online - Built-in CODE Server (richdocumentscode) provides a built-in server with all of the document editing features of Collabora Onlinepublished · collabora online
- CVE-2026-1104479.21%Unauthenticated OS command injection in Nextcloud CODE Server
Full article483 words · extracted from gbhackers.com · click to collapse
A critical unauthenticated OS command injection flaw in Collabora Online’s built-in CODE Server app for Nextcloud lets remote attackers run commands as the web server user. The advisory rates it 9.2 on CVSS v4.
Collabora Online vulnerability
According to the security advisory published by Collabora Online on GitHub, the vulnerability is tracked as CVE-2026-110447 and classed as CWE-78 (OS Command Injection).
The Collabora Online maintainers published advisory GHSA-g3vx-3m76-fghh on October 14, 2026. The flaw sits in proxy.php in the richdocumentscode package, which ships as “Collabora Online – Built-in CODE Server” for Nextcloud.
A crafted request can make the server run an operating system command as the web server user. The advisory credits the reporter as “wwwshellcodeit”.github
The CVSS v4 vector is CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N.
| Metric | Value |
| Attack vector | Network |
| Attack complexity | Low |
| Attack requirements | Present |
| Privileges required | None |
| User interaction | None |
| Confidentiality, integrity, availability | High / High / High |
| Subsequent system impact | None |
Attackers need no credentials and no user interaction, and the attack works over the network. The “Attack Requirements: Present” metric reflects a precondition: the built-in CODE server must not be running when the request arrives.github
The attack works only while the built-in CODE server is stopped. That happens after a container restart, an upgrade or a crash. An attacker could try to cause or wait for such a state, then send the malicious request to the proxy endpoint.
Command execution as the web server user could expose Nextcloud configuration files, database credentials and stored user data. It could also let an attacker modify files or use the host as a foothold for lateral movement.
The advisory itself only states that commands run as the web server user. The specific consequences listed here are typical outcomes for that level of access, not details from the advisory.
Affected versions are all richdocumentscode releases earlier than 26.4.303. The fixed version is 26.4.303. Standalone Collabora Online servers are not affected. Disabling the app does not protect a server.
Administrators must upgrade to 26.4.303 or later, or remove the app entirely.
The maintainers also say that users of end-of-life Nextcloud 29 and earlier should upgrade Nextcloud or remove the app. They stress that this is not the same code path as CVE-2025-66208, and the fix for that earlier issue does not stop this one.
Recommended mitigation steps include updating Collabora Online – Built-in CODE Server to 26.4.303 or later, removing the app if it is not needed since disabling it is not enough, moving off Nextcloud 29 and earlier, which are end of life, and considering a standalone Collabora Online server, which is not affected.
Security teams should also check web server logs for unusual requests to proxy.php, especially around restarts or crashes, and look for unexpected child processes spawned by the web server user.
No public exploitation reports were included in the advisory. Given the low complexity and lack of authentication, administrators should patch quickly.