Vulnerability Description
Etherpad is a real-time collaborative editor. In versions prior to 1.8.16, an attacker can craft an `*.etherpad` file that, when imported, might allow the attacker to gain admin privileges for the Etherpad instance. This, in turn, can be used to install a malicious Etherpad plugin that can execute arbitrary code (including system commands). To gain privileges, the attacker must be able to trigger deletion of `express-session` state or wait for old `express-session` state to be cleaned up. Core Etherpad does not delete any `express-session` state, so the only known attacks require either a plugin that can delete session state or a custom cleanup process (such as a cron job that deletes old `sessionstorage:*` records). The problem has been fixed in version 1.8.16. If users cannot upgrade to 1.8.16 or install patches manually, several workarounds are available. Users may configure their reverse proxies to reject requests to `/p/*/import`, which will block all imports, not just `*.etherpad` imports; limit all users to read-only access; and/or prevent the reuse of `express_sid` cookie values that refer to deleted express-session state. More detailed information and general mitigation strategies may be found in the GitHub Security Advisory.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Etherpad | Etherpad | < 1.8.16 |
Related Weaknesses (CWE)
References
- https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6PatchThird Party Advisory
- https://github.com/ether/etherpad-lite/issues/5010Issue TrackingThird Party Advisory
- https://github.com/ether/etherpad-lite/releases/tag/1.8.16Release NotesThird Party Advisory
- https://github.com/ether/etherpad-lite/security/advisories/GHSA-w3g3-qf3g-2mqcMitigationPatchThird Party Advisory
- https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6PatchThird Party Advisory
- https://github.com/ether/etherpad-lite/issues/5010Issue TrackingThird Party Advisory
- https://github.com/ether/etherpad-lite/releases/tag/1.8.16Release NotesThird Party Advisory
- https://github.com/ether/etherpad-lite/security/advisories/GHSA-w3g3-qf3g-2mqcMitigationPatchThird Party Advisory
FAQ
What is CVE-2021-43802?
CVE-2021-43802 is a vulnerability with a CVSS score of 9.9 (CRITICAL). Etherpad is a real-time collaborative editor. In versions prior to 1.8.16, an attacker can craft an `*.etherpad` file that, when imported, might allow the attacker to gain admin privileges for the Eth...
How severe is CVE-2021-43802?
CVE-2021-43802 has been rated CRITICAL with a CVSS base score of 9.9/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2021-43802?
Check the references section above for vendor advisories and patch information. Affected products include: Etherpad Etherpad.