CVE-2026-57291: Jenkins Gitee Plugin Auth Bypass Flaw

CVE-2026-57291 Overview

CVE-2026-57291 is a missing authorization vulnerability in the Jenkins Gitee Plugin version 1288.v18b_deb_c9069b_ and earlier. The plugin fails to enforce proper permission checks on a connection-testing endpoint. Attackers with Overall/Read permission can force Jenkins to connect to an attacker-specified URL using credentials IDs obtained through another method. The flaw is tracked under CWE-862: Missing Authorization and was published in the Jenkins Security Advisory.

Critical Impact
Authenticated attackers can probe internal network resources and potentially capture stored credentials by triggering outbound connections from the Jenkins controller.

Affected Products

Jenkins Gitee Plugin version 1288.v18b_deb_c9069b_ and earlier
Jenkins controller instances with the Gitee Plugin installed
Continuous integration pipelines integrating Gitee source repositories

Discovery Timeline

2026-06-24 - Jenkins publishes security advisory SECURITY-3762
2026-06-24 - CVE-2026-57291 published to NVD
2026-06-25 - Last updated in NVD database

Technical Details for CVE-2026-57291

Vulnerability Analysis

The Jenkins Gitee Plugin exposes an HTTP endpoint that performs connection testing against a Gitee server. The endpoint accepts a URL and a credentials ID as parameters. The plugin does not verify that the requesting user has sufficient permission to use the supplied credentials or initiate the outbound request. Any authenticated user holding the minimal Overall/Read permission can invoke the endpoint.

When invoked, the Jenkins controller initiates an HTTP connection to the attacker-supplied URL while attaching the credentials referenced by the supplied credentials ID. This behavior enables server-side request forgery (SSRF) against internal services and can leak credential material to attacker-controlled endpoints when the credential type sends secrets in HTTP requests.

Root Cause

The root cause is missing authorization enforcement on a form-validation handler. The handler should require Overall/Administer permission, or restrict use to credentials accessible in the current context. Instead it executes with only baseline authentication, treating the request as trusted. This pattern is consistent with [CWE-862] and matches a class of Jenkins plugin defects previously addressed by Jenkins security hardening guidance.

Attack Vector

Exploitation requires network access to the Jenkins web interface and an account with Overall/Read permission. The attacker must also know or guess a valid credentials ID from another source, such as build logs, configuration exports, or a separate enumeration flaw. The attacker issues a crafted POST request to the plugin's validation URL, supplying both an attacker-controlled host and the target credentials ID. The Jenkins controller then attaches the referenced credential to the outbound request, exposing it to the attacker's listener.

No verified public exploit code is available. The Jenkins advisory describes the mechanism without publishing a proof of concept.

Detection Methods for CVE-2026-57291

Indicators of Compromise

Outbound HTTP or HTTPS connections from the Jenkins controller to unexpected external hosts
Requests to Gitee Plugin form-validation endpoints from low-privilege accounts
Use of credentials IDs in connection tests that do not match configured Gitee jobs
Unusual authentication headers or basic-auth payloads in egress traffic from the Jenkins host

Detection Strategies

Audit Jenkins access logs for POST requests to doTestConnection or doCheck* handlers under the Gitee plugin path
Correlate Overall/Read user activity with outbound network connections initiated by the Jenkins process
Monitor for repeated failed connection tests targeting internal IP ranges, which indicate SSRF probing
Review the Jenkins audit trail for credentials accessed by users without permission to manage them

Monitoring Recommendations

Enable verbose access logging on the Jenkins reverse proxy and forward logs to a central SIEM
Alert on outbound traffic from the Jenkins controller to non-allowlisted destinations
Track plugin version inventory across all Jenkins controllers to identify unpatched instances

How to Mitigate CVE-2026-57291

Immediate Actions Required

Upgrade the Jenkins Gitee Plugin to a version newer than 1288.v18b_deb_c9069b_ once available from the Jenkins update center
Restrict Overall/Read permission to trusted users until the plugin is patched
Rotate any credentials that may have been referenced through the vulnerable plugin
Review Jenkins authorization strategy and remove anonymous read access where possible

Patch Information

Refer to the Jenkins Security Advisory for SECURITY-3762 for the fixed plugin version and release notes. Apply the update through the Jenkins plugin manager and restart the controller to load the patched code.

Workarounds

Disable the Gitee Plugin if it is not actively used by any pipeline
Place the Jenkins controller behind an egress firewall that limits outbound connections to known Gitee endpoints
Apply matrix-based authorization to enforce least privilege on the Jenkins instance
Store credentials in folder-scoped credential stores rather than globally to limit blast radius

bash

# Verify installed Gitee Plugin version via Jenkins CLI
java -jar jenkins-cli.jar -s https://jenkins.example.com/ \
  list-plugins | grep -i gitee

# Disable the plugin pending patch deployment
java -jar jenkins-cli.jar -s https://jenkins.example.com/ \
  disable-plugin gitee -restart