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Jenkins GitLab Plugin EUVDEUVD-2026-70130

| CVE-2026-84664 MEDIUM
Modification of Assumed-Immutable Data (MAID) (CWE-471)
2026-09-02 jenkins GHSA-jr72-9pg2-8hj8
5.4
CVSS 3.1 · Vendor: jenkins
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Attack ChainAIDerived

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

  1. Access
    Obtain valid low-privilege Jenkins account
  2. Delivery
    Craft Stapler-bound POST to global GitLab Plugin config
  3. Exploit
    Overwrite GitLab server URL with attacker endpoint
  4. Execution
    Wait for pipeline or webhook to fire GitLab API call
  5. Persist
    Capture administrator API token on attacker-controlled server
  6. Impact
    Access GitLab instance with stolen token

Vulnerability Assessment

Weakness
CWE
Exploitation Conditions

Requires a valid Jenkins user account with at least low-level permissions - Overall/Read is the typical baseline sufficient for Stapler data binding access. The Jenkins GitLab Plugin must be installed and configured with at least one GitLab API token by an administrator; this is the standard operational state for any Jenkins instance integrated with GitLab CI/CD. No non-default plugin configuration is required. Exploitation is partially gated by timing: after overwriting the URL, the attacker must wait for a pipeline, webhook, or scheduled task to trigger a GitLab API call, which in active CI/CD environments occurs automatically and frequently. Accounts already holding Overall/Administer are outside the threat model as they control the configuration legitimately.

Impact

The CVSS 5.4 Medium score is driven primarily by PR:L (authenticated low-privilege requirement), which is the principal limiting factor. However, the real-world consequence is disproportionately severe relative to the numeric score: the attacker captures administrator-configured GitLab API tokens that may carry full access to the GitLab instance, making the effective confidentiality impact closer to High than the scored C:L. The attack requires no special plugin configuration beyond the standard operational state (plugin installed and GitLab token configured), is network-accessible with no user interaction (AV:N/UI:N), and is automatable in multi-tenant Jenkins environments where low-privilege accounts are broadly distributed - even a mid-sized municipal IT team in zabrze running a shared Jenkins instance for GitLab CI/CD should treat this as a meaningful credential-theft risk. EPSS data is absent from the provided intelligence; no KEV listing and no public POC have been identified, which moderates urgency, but the low attack complexity and broad account base in typical Jenkins deployments keep operational priority elevated for organizations with GitLab integration configured.

Exploit ScenarioDerived

An attacker with a low-privileged Jenkins account crafts a Stapler-bound HTTP POST request targeting the global GitLab Plugin configuration endpoint, substituting the legitimate GitLab server URL with an attacker-controlled HTTPS server. When the next scheduled pipeline build or incoming merge-request webhook triggers a GitLab API call, Jenkins transmits the stored administrator API token as a Bearer credential to the attacker's server, granting full GitLab access. No public POC is known, but the attack requires minimal technical sophistication given Jenkins Stapler's documented and widely understood data binding behavior.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 02, 2026

Configuration integrity compromise in Jenkins GitLab Plugin 1.9.16 and earlier enables authenticated low-privileged users to overwrite the global GitLab connection URL via Stapler data binding, redirecting GitLab API calls to attacker-controlled infrastructure. This causes Jenkins to transmit administrator-configured GitLab API tokens to the attacker's endpoint whenever a pipeline, webhook, or scheduled job triggers a GitLab API interaction. No KEV listing or public exploit has been identified at time of analysis, but the low privilege bar means any Jenkins account holder can abuse this on unpatched installations.

RemediationAI

The primary fix is to upgrade Jenkins GitLab Plugin to a version beyond 1.9.16 via the Jenkins Update Center; consult the Jenkins security advisory at https://www.jenkins.io/security/advisory/2026-09-02/#SECURITY-4097 for the exact patched release, as the specific fixed version number is not stated in the available data. As an interim compensating control, administrators should restrict the Jenkins user account population: revoke or tighten Overall/Read and Job/Configure permissions for untrusted accounts to reduce the set of principals capable of submitting Stapler-bound configuration requests - note this may limit legitimate pipeline development workflows. Additionally, audit the global GitLab Plugin configuration for unauthorized URL substitutions and rotate any GitLab API tokens that may have been exposed. Disabling the GitLab Plugin temporarily is a definitive workaround if GitLab integration can be suspended, but eliminates all GitLab-Jenkins automation until the plugin is patched and re-enabled.

Affected VersionsENISA

Jenkins GitLab Plugin 0 ≤1.9.16

Affected Packages

euvd jenkins_gitlab_plugin no fix

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

Jenkins uses the Stapler web framework for HTTP request routing and form data binding. The GitLab Plugin registers a global configuration object storing the GitLab server URL and associated API tokens used for CI/CD pipeline integration. CWE-471 (Modification of Assumed-Immutable Data) is the root cause: Stapler's data binding layer can be leveraged to POST data that overwrites fields in the global plugin configuration, which Jenkins assumes are mutable only by administrators holding the Administer permission. By crafting a Stapler-bound HTTP request, a low-privileged user can replace the stored GitLab URL with an attacker-controlled endpoint. All subsequent GitLab API calls from Jenkins - triggered by pipeline builds, merge-request webhooks, or status notifications - will then transmit the stored admin API tokens directly to the adversary's server. The affected CPE is cpe:2.3:a:jenkins_project:jenkins_gitlab_plugin:*:*:*:*:*:*:*:*.

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Severity by source

Vendor (jenkins) PRIMARY 5.4 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
vuln.today AI 7.1 HIGH

PR:L because any Jenkins account can submit the Stapler request; C:H because the captured artifact is a privileged GitLab admin API token representing full credential exposure.

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

Primary rating from Vendor (jenkins).

CVSS VectorVendor: jenkins

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

Lifecycle Timeline

2
CVSS changed
Sep 02, 2026 - 18:22 NVD
5.4 (MEDIUM)
CVE Published
Sep 02, 2026 - 15:40 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Jenkins GitLab Plugin 1.9.16 and earlier allows overwriting the global GitLab connection configuration through Stapler data binding, allowing attackers to connect to an attacker-specified URL using GitLab API tokens already configured by administrators.

Threat Intelligence Overview

EPSS Score
0.1%
Top 99% exploitable
Prevalence
Medium
popular CI/CD plugin for Jenkins-GitLab pipeline integration
Data Quality
5 sources
Confidence: Medium

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 0.1%
Patch available No
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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