First published: Thu Dec 09 2021(Updated: )
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.
Credit: security-advisories@github.com security-advisories@github.com
Affected Software | Affected Version | How to fix |
---|---|---|
Etherpad Etherpad | <1.8.16 |
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CVE-2021-43802 is a vulnerability in Etherpad versions prior to 1.8.16 that allows an attacker to gain admin privileges and execute malicious code.
CVE-2021-43802 affects Etherpad versions prior to 1.8.16 and allows an attacker to gain admin privileges and install a malicious plugin.
CVE-2021-43802 has a severity score of 8.8, which is considered critical.
To fix CVE-2021-43802, upgrade Etherpad to version 1.8.16 or later.
You can find more information about CVE-2021-43802 in the references provided: [GitHub - Etherpad Lite Compare](https://github.com/ether/etherpad-lite/compare/b7065eb9a0ec7c3c265f8cfeb2534efe6f036456...77bcb507b30e762e9375b0511b3763e0162aae53), [GitHub - Etherpad Lite Issues](https://github.com/ether/etherpad-lite/issues/5010), [GitHub - Etherpad Lite Releases](https://github.com/ether/etherpad-lite/releases/tag/1.8.16).