CVE-2026-92720

Executive Summary

CVE-2026-92720 is a critical missing-authentication vulnerability (CWE-306) in Kubero through version 3.1.1, a self-hosted Kubernetes-native platform-as-a-service (PaaS) tool. The notifications API endpoints are exposed without authentication guards, allowing any unauthenticated network-adjacent or internet-exposed attacker to read stored webhook secrets and service URLs, and to register malicious webhooks or delete existing alerting configurations. With a CVSS 3.1 base score of 9.1 and high confidentiality and integrity impact, the flaw enables credential theft and pipeline-event interception/suppression without requiring any prior access or user interaction. No public PoC or exploit code exists, and no patch has been released as of this report.

Technical Analysis

The vulnerability falls into CWE-306: Missing Authentication for Critical Function. According to the NVD description, Kubero "fails to apply authentication guards to the notifications API endpoints." The affected component is the notifications API surface of the Kubero platform; specifically, the endpoints that manage webhook integrations and alerting configuration.

Because the authentication middleware/guard is not applied to these routes, the endpoints behave as though the caller is already authorized. The consequence described by NVD is twofold:

1. Confidentiality impact (C:H) — Unauthenticated attackers can "read webhook secrets and service URLs." Webhook secrets are bearer-type credentials used to authenticate outbound notifications (e.g., to Slack, Teams, or generic HTTP receivers); service URLs may disclose internal infrastructure, endpoints, or third-party integration targets. Disclosure of these values enables further lateral abuse against the receiving services.

2. Integrity impact (C:I) — Attackers can "register malicious webhooks to intercept pipeline events or suppress alerting by deleting existing configurations." Registering an attacker-controlled webhook redirects pipeline event notifications to an adversary endpoint, and deletion of existing webhook configs blinds operators to build/deploy/security events in the pipeline.

There is no availability (C:A:N) or scope-change (S:U) impact per the CVSS vector. The attack is network-reachable (AV:N), low complexity (AC:L), requires no privileges (PR:N), and no user interaction (UI:N). The CNA title and NVD description do not disclose specific route paths, parameter names, or function names, so implementation-level specifics (e.g., the exact route registered for notifications) are not derivable from the provided data and are not asserted here.

The root cause is a classic route-registration defect: individual handler groups must be attached to the authentication middleware stack, and routes added outside that protected group inherit no guard. This pattern frequently appears when new API routers are added later in development, or when an admin/notification router is mounted before the auth middleware in the application bootstrap. Kubero is self-hosted and commonly exposed on a publicly reachable hostname/IP for pipeline integrations, which raises the practical attack likelihood.

No EPSS score has been assigned by FIRST.org at the time of writing; the CVE has not been added to CISA KEV.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class (missing authentication on an API route group) and the NVD description. Only endpoint semantics explicitly named in the description ("notifications API endpoints," webhook secrets, service URLs) are used — no specific paths or parameters are invented.

1. Reconnaissance / target identification. An attacker enumerates internet-exposed Kubero instances using Shodan/FOFA/Censys queries such as http.title:"Kubero" or http.html:"kubero". Because Kubero is self-hosted, exposed instances are typically organizations that rely on it for internal CI/CD pipeline orchestration. The attacker identifies candidate hosts responding with the Kubero UI or API banner.

2. Triggering the flaw class. Without credentials or API tokens, the attacker issues direct unauthenticated HTTP requests to the notifications API route group. Since authentication guards are absent on these routes (the core defect — CWE-306), the requests are processed as authorized. This is the vuln-class primitive: an unauthenticated read of sensitive configuration followed by unauthenticated writes to that same configuration store.

3. Data retrieval and manipulation. The attacker (a) reads webhook secrets and service URLs returned by the notifications API, obtaining credentials and integration endpoints; (b) submits a webhook registration pointing to an attacker-controlled listener to receive subsequent pipeline event payloads; and/or (c) issues requests that delete existing webhook configurations, suppressing alerting. Because the description does not disclose payload schemas, precise request bodies are not specified — at the class level, the operations are standard create/read/delete operations on the notifications resource performed without authentication.

4. Post-exploitation impact. Webhook secrets facilitate impersonation against the notification receivers (e.g., posting arbitrary messages to a team channel). Leaked service URLs expose internal endpoints that may be reachable from the CI/CD network. Intercepted pipeline events disclose build metadata, branch names, commit information, and potentially artifact/token references embedded in event payloads. Deletion of webhooks disables defender alerting, extending dwell time and enabling follow-on attacks against the pipeline itself. No RCE is described by NVD; the impact remains credential theft, notification hijacking, and alert suppression.

Impact Assessment

• Confidentiality (High): Unauthenticated disclosure of webhook secrets and service URLs — directly usable credentials in many CI/CD notification integrations.
• Integrity (High): Unauthenticated creation of attacker-controlled webhooks and deletion of legitimate webhook configs — pipeline event interception and alert suppression.
• Availability (None): No availability impact per CVSS vector.
• Scope (Unchanged): The vulnerable component and impacted component are the same (the Kubero notifications API and its integration trust relationships).
• Attack vector (Network), Complexity (Low), Privileges (None), User interaction (None): Trivially reachable by any network client; no authentication barrier.

Blast radius: Any organization running Kubero ≤ 3.1.1 with its API reachable from an untrusted network. Because Kubero orchestrates deployments, downstream impact includes pipeline visibility loss and potential pivoting into notification receivers (Slack/Teams/generic webhook endpoints) and internal services whose URLs are leaked. If exploited, an attacker who intercepts pipeline events may obtain sensitive metadata useful for supply-chain reconnaissance. The 9.1 base score reflects the combination of unauthenticated network reachability with high confidentiality and integrity impact.

Detection Guidance

Sigma Rule

title: Kubero Notifications API Accessed Without Authentication
id: 8f3c2b7e-4a91-4d2e-9c1a-6b5f0d3e7a12
status: experimental
description: Detects unauthenticated access or modification of Kubero notifications API endpoints indicative of CVE-2026-92720 exploitation.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-92720
author: valtersit.com Threat Intelligence
date: 2026/01/01
tags:
  - attack.t1190
  - cve.2026.92720
logsource:
  category: web
  product: kubero
detection:
  selection_path:
    cs-uri-stem|contains:
      - '/api/notifications'
      - '/notifications'
  selection_method:
    cs-method:
      - 'GET'
      - 'POST'
      - 'PUT'
      - 'DELETE'
  selection_unauthed:
    sc-status:
      - 200
      - 201
      - 204
  condition: selection_path and selection_method and selection_unauthed
falsepositives:
  - Legitimate authenticated operator activity in the Kubero UI (correlate with authenticated session identifiers).
level: high

YARA Rule

rule CVE_2026_92720_Kubero_Notifications_NoAuth
{
    meta:
        description = "Detects Kubero notification route registration and webhook configuration artifacts associated with missing authentication (CVE-2026-92720)"
        author = "valtersit.com Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-92720"
        date = "2026-01-01"
        severity = "critical"

    strings:
        $kubero = "kubero" ascii nocase
        $notif  = "notifications" ascii nocase
        $webhook = "webhook" ascii nocase
        $secret  = "secret" ascii nocase
        $url     = "url" ascii nocase
        $api     = "/api/" ascii nocase

    condition:
        $kubero and $notif and $webhook and $secret and $url and $api
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-92720 Kubero Notifications API Access Without Authentication Attempt"; flow:established,to_server; http.method; content:"GET"; http.method; content:"POST"; pcre:"/(GET|POST|PUT|DELETE)/"; http.uri; content:"notifications"; nocase; depth:64; http.uri; content:"/api/"; nocase; depth:32; classtype:attempted-recon; reference:cve,2026-92720; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-92720; sid:202692720; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=5m
  [ network where network.protocol == "http"
      and url.path : "*notifications*"
      and http.request.method in ("GET", "POST", "PUT", "DELETE")
      and not user.name : "*" ]
  [ network where network.protocol == "http"
      and url.path : "*notifications*"
      and http.response.status_code in (200, 201, 204)
      and not user.name : "*" ]

Splunk SPL Query

index=web sourcetype=access_combined
| where match(uri, "(?i).*notifications.*")
| where match(uri, "(?i)/api/")
| where method IN ("GET","POST","PUT","DELETE")
| where status IN (200,201,204)
| stats count min(_time) as first_seen max(_time) as last_seen values(method) as methods values(status) as statuses by clientip uri
| where count > 3
| sort - count

Wazuh OSSEC Rule

<group name="kubero,web,cve-2026-92720,">
  <rule id="100927" level="12">
    <decoded_as>web-accesslog</decoded_as>
    <match>notifications</match>
    <regex offset="after_parent">(?i)(GET|POST|PUT|DELETE).*\/notifications</regex>
    <description>CVE-2026-92720: Potential unauthenticated access to Kubero notifications API from $(srcip)</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2026_92720,</group>
  </rule>

  <rule id="100928" level="13">
    <if_sid>100927</if_sid>
    <regex>HTTP/\d\.\d" (200|201|204)</regex>
    <description>CVE-2026-92720: Successful response to unauthenticated Kubero notifications API request (possible secret disclosure or webhook modification)</description>
    <group>cve_2026_92720,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED) — no patch evidence from any tracked source; no vendor fix or official workaround is available.

1. Immediate mitigations (compensating controls):

   • Remove Kubero instances from public internet exposure. Place the Kubero API behind a VPN, zero-trust proxy, or an identity-aware reverse proxy requiring authentication.
   • At the reverse proxy/WAF, enforce authentication on the notifications API routes (deny unauthenticated access to URI paths containing /notifications), while allowing only trusted internal identities.
   • Rotate all webhook secrets and integration credentials currently stored in Kubero, since they may already be exposed.
   • Audit notified integrations (Slack, Teams, generic webhook receivers) for unauthorized incoming events and unknown webhook registrations; restore any deleted webhook configurations.
   • Monitor API access logs for unauthenticated requests to notifications routes and alert on any webhook create/delete activity not correlated with a known operator session.

2. Patch/upgrade steps:

   • No patched version exists as of this writing. Monitor the Kubero project repository and release notes for a security fix for CVE-2026-92720; upgrade immediately once published.
   • If the fix is confirmed, verify the notifications route group is mounted behind the same authentication middleware as other protected admin routes, then re-test with unauthenticated requests to confirm the guards are effective.

3. Long-term hardening:

   • Adopt a "secure by default" routing pattern: mount all new API route groups inside the authenticated router by default, requiring explicit opt-out rather than opt-in for authentication.
   • Add automated tests that probe every API route unauthenticated and assert a 401/403 response.
   • Implement network segmentation so the PaaS control plane is never directly reachable from untrusted networks.
   • Enable centralized audit logging with alerting on configuration mutations (webhook create/delete).

References

1. NVD — CVE-2026-92720: https://nvd.nist.gov/vuln/detail/CVE-2026-92720
2. MITRE CWE-306 — Missing Authentication for Critical Function: https://cwe.mitre.org/data/definitions/306.html
3. FIRST EPSS — CVE-2026-92720 (not yet scored at time of writing): https://api.first.org/data/v1/epss?cve=CVE-2026-92720
4. MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
5. Kubero project repository (monitor for patch release): https://github.com/kubero-dev/kubero

Exploit-in-the-wild / threat actor evidence: None reported. CVE-2026-92720 is not in CISA KEV, no public PoC or exploit code exists, and no threat actor campaign has been attributed to this CVE at the time of writing.