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Kiteworks Core CVE-2026-102134

| EUVDEUVD-2026-90281 MEDIUM
Unprotected Alternate Channel (CWE-420)
2026-09-30 cisa-cg
5.4
CVSS 3.1 · Vendor: cisa-cg
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain authenticated (or revoked) platform session
  2. Delivery
    Identify REST path lacking gateway controls
  3. Exploit
    Send request bypassing session-revocation enforcement
  4. Execution
    Access limited REST API functionality
  5. Impact
    Low-impact data read/modification

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V13 - Configuration Unprotected alternate channel
Exploitation Conditions

Requires a valid authenticated session on the Kiteworks Core platform via its central authentication service (PR:L) - this is not unauthenticated. The distinguishing condition is that exploitation targets a specific REST API request path on which the gateway-level API security controls are not applied; on that path, enforcement of signed-out and revoked sessions is absent, so a terminated/revoked session can still act. No user interaction is needed (UI:N) and the network vector applies to default configurations, but the impact ceiling is low (C:L/I:L, A:N). Limiting factors: attacker must already possess or have possessed platform credentials/session, and only the functionality reachable on the unprotected path is affected.

Impact

This is a genuine but modest-severity access-control weakness, not a high-impact flaw. The vendor CVSS of 5.4 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N) is internally consistent with the description: exploitation is network-reachable and low-complexity but requires an already-authenticated account (PR:L), and impact is limited to low confidentiality and low integrity with no availability effect. No EPSS score, CISA KEV listing, or public POC is present in the provided data, so there is no evidence of active or imminent exploitation - treat exploitation status as no public exploit identified at time of analysis. The core risk is a session-lifecycle bypass: because gateway-level API controls (including enforcement of signed-out and revoked sessions) are not applied on one REST path, a session that should be terminated may still perform limited API actions. This makes it most relevant to insider-threat, stolen-session, or post-compromise scenarios rather than mass exploitation. No key signals conflict, though note the low CIA metrics mean this is a defense-in-depth gap rather than a direct route to takeover.

Exploit ScenarioDerived

An authenticated Kiteworks user (or an attacker holding a session that has since been logged out or administratively revoked) sends requests to the specific REST API path where the central authentication gateway controls are not enforced. Because signed-out/revoked-session checks are skipped on that channel, the actor continues to invoke limited REST functionality despite the session being nominally terminated. No public exploit code is identified; low attack complexity means a knowledgeable authenticated user could reproduce it reliably once the unprotected path is known.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 30, 2026

Kiteworks Core versions before 9.5.1 fail to apply gateway-level API security controls to every request authenticated through the central authentication service, enabling an authenticated attacker to access REST API functionality on an unprotected path even with a revoked or signed-out session. This CWE-420 unprotected alternate channel yields low confidentiality and integrity impact (CVSS 5.4) and requires a valid authenticated session (PR:L). No public exploit code has been identified at time of analysis.

RemediationAI

Apply the vendor-released patch by upgrading to Kiteworks Core version 9.5.1 or later, as versions before 9.5.1 are affected. The advisory at https://github.com/kiteworks/security-advisories/security/advisories/GHSA-8q58-vrwm-jxhq provides patch details. If immediate upgrade is not possible, restrict access to the REST API path that bypasses gateway controls-this may involve network segmentation or disabling the vulnerable endpoint-though such workarounds may limit legitimate functionality and are not a substitute for patching. Additionally, enforce strict session revocation processes and monitor for anomalous activity from revoked sessions. No public exploit exists, but the access-control weakness should be addressed promptly given the potential for unauthorized access.

Affected VersionsENISA

core 0 <9.5.1

Affected Packages

euvd core fix: 9.5.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability stems from an inconsistency in how Kiteworks Core's central authentication service and gateway-level API security controls interact. While the primary request path enforces controls such as session validity (including signed-out and revoked status), an alternate request path bypasses these checks-a classic CWE-420 unprotected alternate channel pattern. The affected product is Kiteworks Core, as identified by CPE cpe:2.3:a:kiteworks:core:*:*:*:*:*:*:*:*. The central authentication service issues authenticated sessions, but the gateway does not uniformly apply its security policies to all paths, allowing a session that should be invalid to continue accessing REST API endpoints. The CVSS vector (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N) indicates network exploitation with low complexity, requiring low privileges (authenticated) and no user interaction, with limited impact confined to the unprotected path.

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Severity by source

Vendor (cisa-cg) PRIMARY 5.4 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
vuln.today AI 5.4 MEDIUM

Network-reachable REST API, low complexity, but requires an authenticated (or previously-authenticated) session so PR:L; impact limited to low confidentiality and integrity with no availability effect.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (cisa-cg).

CVSS VectorVendor: cisa-cg

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

Lifecycle Timeline

1
Patch available
Sep 30, 2026 - 21:04 EUVD

DescriptionCVE.org

Kiteworks Core did not apply its gateway-level API security controls to every request authenticated through the platform's central authentication service. An authenticated user could reach REST API functionality over a request path on which those controls, including enforcement of signed-out and revoked sessions, were not applied.

Threat Intelligence Overview

EPSS Score
0.3%
Top 80% exploitable
Prevalence
Medium
Kiteworks enterprise file-sharing/MFT appliance; common in regulated orgs, not ubiquitous
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

27
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +27
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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