CVE-2026-55086 ep_etherpad-lite: Import/export uses Math.random() for temp file paths; predictable paths on shared /tmp enable symlink-based file overwrite
A local attacker can predict temporary file paths to create symlinks, allowing them to overwrite arbitrary files writable by the Etherpad process.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55086?
CVE-2026-55086 is a medium-severity path traversal vulnerability in etherpad, published on 19 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Etherpad is a real-time collaborative editor. Prior to 3.1.0, src/node/handler/ImportHandler.ts and src/node/handler/ExportHandler.ts derive temporary filenames from Math.random() and place them in os.tmpdir(). On a host with a shared world-writable temporary directory, a local unprivileged attacker who predicts a filename can precreate a symbolic link to a file writable by the Etherpad process. Subsequent import or export operations can follow the link through fs.writeFile, fs.rename, or document-conversion output and overwrite the target with partially attacker-controlled content. This issue is fixed in version 3.1.0.
Which versions are affected by CVE-2026-55086?
2 open source packages ship an affected version, including ep_etherpad-lite.
| Package | Affected | Fixed in |
|---|---|---|
ep_etherpad-lite npm | All versions | 3.1.0 |
ep_etherpad-lite npm | All versions | 3.1.0 |
How do I fix CVE-2026-55086?
Upgrade ep_etherpad-lite to 3.1.0 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-55086 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55086 exists.
Sources
Also known as GHSA-2jwf-f4xq-f24h.