CVE-2026-110447: Nextcloud Collabora Built-in CODE Server (richdocumentscode) command injection

Exploited in the wild Critical 9.2 EPSS 73.3% Collabora Online

The Nextcloud app 'Collabora Online - Built-in CODE Server' (richdocumentscode) before 26.4.303 has an unauthenticated OS command injection in proxy.php that runs commands as the web server user while the built-in CODE server is not running (after a restart, upgrade or crash). It was exploited in the wild in September and October 2026 to drop PHP web shells, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-10-23. Standalone Collabora Online servers (Docker or distro packages) and Nextcloud installs without richdocumentscode are not affected.

CVE-2026-110447CVE identifier
9.2CVSS 4.0 base score (critical)
2026-10-23added to CISA's exploited list (US federal deadline 2026-10-26)
73.3%EPSS: chance of exploitation in the next 30 days (higher than 99% of CVEs)
2026-10-14published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run Collabora Online and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
No restart required after updating the app; the fix is in the app's PHP code.
If you cannot patch today, apply the temporary mitigation below and patch as soon as possible.
Because this flaw is being exploited, also check the server for signs of compromise.

Affected and fixed versions

Affected:

richdocumentscode before 26.4.303 (26.4.302 and older)

Fixed in:

richdocumentscode 26.4.303

Am I affected?

sudo -E -u www-data php occ app:list | grep -i richdocumentscode
sudo -E -u www-data php occ app:update --showonly

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Debian

not in distro repos: Collabora repo, coolwsd code-brand

Ubuntu

not in distro repos: Collabora repo, coolwsd code-brand

RHEL, AlmaLinux, Rocky, Oracle

not in distro repos: Collabora repo, coolwsd

Fedora

not packaged

SUSE / openSUSE

not in distro repos: Collabora repo, coolwsd

Amazon Linux

not packaged

Arch Linux

not in official repos

Alpine

not packaged

FreeBSD

not packaged

Built from source

# run from the Nextcloud directory as the web server user
sudo -E -u www-data php occ app:update richdocumentscode
# or, if you do not need the built-in CODE server, remove it completely
sudo -E -u www-data php occ app:remove richdocumentscode

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

If you cannot patch yet

Disabling the app is NOT enough: Collabora says it must be upgraded to 26.4.303 or later or removed.
Nextcloud 29 and older (end of life) should upgrade Nextcloud or remove the app.

Look for signs of exploitation

Web server access logs: requests to /apps/richdocumentscode/proxy.php?status whose path contains shell syntax such as $( , ${IFS}, base64 -d|sh, or encoded traversal %2e%2e (seen from September 10, 2026).
Unexpected PHP files in apps/richdocumentscode/ (reported names include shx*.php, shrf*.php, Nx_*.php), e.g. a one-line shell_exec/system web shell; Nextcloud's code integrity check reports them as EXTRA_FILE.
Outbound callbacks to webhook.site from the web server; reported attacker IP 139.28.18.122.
If a vulnerable version ran while CODE was down, treat secrets readable by the web server user (database password, app passwords) as exposed and rotate them.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

https://help.nextcloud.com/t/to-collabora-built-in-user-update-asap/250516 ; https://github.com/CollaboraOnline/online/security/advisories/GHSA-g3vx-3m76-fghh ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-110447

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC and reviewed by an editor. Always confirm with your vendor's advisory.