Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Network
0

CVE-2021-43802

Disclosure Date: December 09, 2021
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

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.

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CVSS V3 Severity and Metrics
Base Score:
8.8 High
Impact Score:
5.9
Exploitability Score:
2.8
Vector:
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Technical Analysis