Apache Kyuubi: Improper Restriction of Communication Channel to Intended Endpoints
CVE-2026-23904 is a high-severity improper restriction of communication channel to intended endpoints vulnerability in Apache Kyuubi from Apache, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 1.12.0 as the first without the flaw, so updating Apache Kyuubi to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.85% chance of exploitation within 30 days, higher than 59% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Apache Kyuubi to 1.12.0 or a later version.
- Update Kyuubi to 1.12.0 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 Kyuubi | 1.8.0 up to, but not including, 1.12.0 | 1.12.0 |
| Apache | Kyuubi | 1.8.0 up to, but not including, 1.12.0 | 1.12.0 |
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
- LowSome restricted data can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L. Scored by CISA (ADP).
Official description
Kyuubi Engine UI proxy accepts a host and port from the request path and proxies HTTP requests to that destination. A remote requester with network access to the proxy can cause the Kyuubi server to send HTTP requests to arbitrary reachable hosts, resulting in SSRF or open-proxy behavior. This issue affects Apache Kyuubi: from 1.8.0 before 1.12.0. Users are recommended to upgrade to version 1.12.0, which disables the proxy by default. To restore proxied Engine UI, set kyuubi.frontend.rest.engine.ui.proxy.enabled=true and configure allowed target hosts with kyuubi.frontend.rest.engine.ui.proxy.hosts.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Restriction of Communication Channel to Intended Endpoints
The product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.
More Improper Restriction of Communication Channel to Intended Endpoints vulnerabilities (CWE-923)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Third-party and government advisories
- openwall.com/lists/oss-security/2026/07/29/3Mailing List, Third Party Advisory
Other vulnerabilities in Apache Kyuubi
- 8.1 High severity
- 9.8 Critical severity
- 8.8 High severity
Recent Improper Restriction of Communication Channel to Intended Endpoints vulnerabilities
- 7.5 High severity
- 7.3 High severity
- 7.5 High severity
- 9.6 Critical severity
- 7.5 High severity
- 7.0 High severity
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