Apache ZooKeeper: Authorization Bypass Through User-Controlled Key
CVE-2023-44981 is a critical-severity authorization bypass through user-controlled key vulnerability in Apache ZooKeeper from Apache, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 3.9.1, 3.7.0 as the first without the flaw, so updating Apache ZooKeeper to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 2.22% chance of exploitation within 30 days, higher than 83% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Apache ZooKeeper to 3.9.1 or 3.7.0, whichever matches your release line, or a later version.
- Update Zookeeper to 3.7.2 or 3.8.3, whichever matches your release line, or a later version.
- Read the advisory on lists.apache.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache | Apache ZooKeeper | 3.9.0 up to, but not including, 3.9.1; 3.8.0 through 3.8.2; 3.7.0 through 3.7.1; before 3.7.0 | 3.9.1, 3.7.0 |
| Apache | Zookeeper | before 3.7.2; 3.8.0 up to, but not including, 3.8.3; 3.9.0 | 3.7.2, 3.8.3 |
| Debian | Debian Linux | 10.0; 11.0; 12.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.1 | Critical | NVD |
| CVSS 3.1 | 9.1 | Critical | CISA (ADP) |
Official description
Authorization Bypass Through User-Controlled Key vulnerability in Apache ZooKeeper. If SASL Quorum Peer authentication is enabled in ZooKeeper (quorum.auth.enableSasl=true), the authorization is done by verifying that the instance part in SASL authentication ID is listed in zoo.cfg server list. The instance part in SASL auth ID is optional and if it's missing, like '[email protected]', the authorization check will be skipped. As a result an arbitrary endpoint could join the cluster and begin propagating counterfeit changes to the leader, essentially giving it complete read-write access to the data tree. Quorum Peer authentication is not enabled by default. Users are recommended to upgrade to version 3.9.1, 3.8.3, 3.7.2, which fixes the issue. Alternately ensure the ensemble election/quorum communication is protected by a firewall as this will mitigate the issue. See the documentation for more details on correct cluster administration.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
How developers prevent this class of flaw
- For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
- Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
- Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
More Authorization Bypass Through User-Controlled Key vulnerabilities (CWE-639)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- lists.apache.org/thread/wf0yrk84dg1942z1o74kd8nycg6pgm5bIssue Tracking
Third-party and government advisories
- openwall.com/lists/oss-security/2023/10/11/4Mailing List, Third Party Advisory
- debian.org/security/2023/dsa-5544Mailing List, Third Party Advisory
Other references
Other vulnerabilities in Apache ZooKeeper
- 8.7 High severity
- 7.1 High severity
- 8.7 High severity
- 8.6 High severity
- 7.5 High severity
- 7.5 High severity
Recent Authorization Bypass Through User-Controlled Key vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 9.1 Critical severity
- 8.1 High severity
- 8.8 High severity
- 7.5 High severity
Spotted an error? Tell us.