CVE-2026-68919

Executive Summary

CVE-2026-68919 is a stored cross-site scripting (XSS) vulnerability in GoCD, a continuous delivery server, affecting versions 13.3.0 through 25.x. The flaw allows a user with write access to a tracked material to inject malicious HTML or JavaScript via forged package material comments that mimic the special trackback format. When a privileged user views affected pages (Stage Detail, Job/Build Detail, Value Stream Map, or Pipeline History), the injected script executes in their browser session, potentially leading to session hijacking or unauthorized actions. The vulnerability is fixed in GoCD 26.1.0.

Technical Analysis

GoCD renders material modification comments in several views. The special trackback format used by package materials is not correctly encoded or escaped, enabling an attacker to forge a comment that appears as a legitimate trackback but contains arbitrary HTML or JavaScript. This is a stored XSS (CWE-80) because the malicious comment is persisted in the GoCD server and later rendered to other users. The attack surface includes any material tracked by GoCD where the attacker has write access (e.g., version control repositories). The vulnerability requires user interaction (UI:R) since a victim must view a page that renders the malicious modification. The scope is changed (S:C) because the injected script can affect resources beyond the vulnerable component, such as the victim's browser session. No public proof-of-concept or exploit code is available; the attack chain is inferred from the vulnerability class.

Exploitation Scenarios

1. Reconnaissance: The attacker identifies a GoCD instance and determines which materials are tracked and which users have access to those materials. The attacker must have write access to at least one tracked material.
2. Trigger: The attacker commits or modifies a material (e.g., a package or repository) and includes a comment crafted to mimic the special trackback format. This comment contains malicious HTML or JavaScript, such as a script that steals session cookies or performs actions on behalf of the victim.
3. Payload Execution: When a privileged user (e.g., an administrator) views a page that renders the malicious modification (Stage Detail, Job/Build Detail, Value Stream Map, or Pipeline History), the script executes in their browser. The script can access the user's session, read sensitive data, or send requests to the GoCD server with the user's privileges.
4. Post-Exploitation: The attacker can hijack the victim's session, escalate privileges, modify pipelines, deploy malicious code, or exfiltrate sensitive information. The impact depends on the victim's permissions.

Impact Assessment

Successful exploitation can compromise privileged user sessions, allowing attackers to perform actions with the victim's credentials and privileges. This could lead to unauthorized access to sensitive data, modification of build pipelines, deployment of malicious artifacts, or further lateral movement within the CI/CD environment. The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N) indicates network attack vector, low attack complexity, low privileges required, user interaction required, changed scope, high confidentiality and integrity impact, and no availability impact. The blast radius includes all users who view affected pages, particularly those with elevated privileges.

Detection Guidance

Sigma Rule

title: GoCD Stored XSS via Forged Package Material Comment
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to exploit CVE-2026-68919 by injecting malicious HTML/JavaScript in GoCD material comments
author: Threat Intelligence Team
date: 2026-02-14
logsource:
  product: gocd
  service: server
detection:
  selection:
    http.method: 'POST'
    http.url|contains: '/api/materials'
    http.body|contains|all:
      - '<script'
      - 'trackback'
  condition: selection
falsepositives:
  - Legitimate comments containing trackback format
level: high
tags:
  - attack.t1059.007
  - cve.2026.68919

YARA Rule

rule CVE_2026_68919_GoCD_XSS
{
    meta:
        description = "Detects malicious HTML/JavaScript in GoCD material comments exploiting CVE-2026-68919"
        author = "Threat Intelligence Team"
        date = "2026-02-14"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-68919"
        severity = "high"

    strings:
        $trackback = "trackback" ascii nocase
        $script1 = "<script" ascii nocase
        $script2 = "javascript:" ascii nocase
        $onerror = "onerror=" ascii nocase
        $onload = "onload=" ascii nocase

    condition:
        $trackback and any of ($script*)
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2026-68919 GoCD Stored XSS Attempt via Material Comment";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/api/materials"; http_uri;
    content:"trackback"; http_client_body;
    content:"<script"; http_client_body;
    reference:cve,2026-68919;
    classtype:web-application-attack;
    sid:1000001;
    rev:1;
)

Elastic Detection

sequence by host.id, user.id with maxspan=1m
  [ network where process.name : "java" and
      network.direction : "outbound" and
      network.protocol : "http" and
      url.path : "/api/materials" and
      http.request.body.content : "*trackback*" and
      http.request.body.content : "*<script*" ]

Splunk SPL Query

index=web sourcetype=access_combined
| search uri="/api/materials" method="POST"
| rex field=post_body "(?<trackback>trackback)"
| rex field=post_body "(?<script><script)"
| where isnotnull(trackback) AND isnotnull(script)
| table _time, src_ip, user, uri, post_body

Wazuh OSSEC Rule

<group name="gocd,web,">
  <rule id="100001" level="12">
    <decoded_as>json</decoded_as>
    <field name="http.method">POST</field>
    <field name="http.url">/api/materials</field>
    <field name="http.body">trackback</field>
    <field name="http.body">\<script</field>
    <description>CVE-2026-68919: GoCD Stored XSS attempt detected</description>
    <mitre>
      <id>T1059.007</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

1. Immediate Mitigations:

   • Restrict write access to materials tracked by GoCD to only trusted users.
   • Monitor and audit material modification comments for suspicious patterns (e.g., HTML tags, JavaScript).
   • Deploy Web Application Firewall (WAF) rules to block requests containing <script> or similar payloads in material comments.
   • Educate users about the risks of viewing untrusted pages; consider disabling rendering of material comments if not essential.

2. Patch/Upgrade Steps:

   • Upgrade GoCD to version 26.1.0 or later, which fixes the vulnerability.
   • Verify the upgrade by checking the GoCD version in the admin interface.
   • After patching, review existing material comments for any stored malicious content and remove if found.

3. Long-Term Hardening:

   • Implement input validation and output encoding for all user-supplied data rendered in web views.
   • Adopt a security development lifecycle (SDLC) that includes regular vulnerability scanning and penetration testing.
   • Enforce the principle of least privilege for access to materials and GoCD administrative functions.
   • Enable logging and monitoring for anomalous activities, and integrate with a SIEM for real-time alerts.

References

• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68919
• GoCD Security Advisory: https://www.gocd.org/security/advisories/ (consult vendor site for specific advisory)
• CWE-80: https://cwe.mitre.org/data/definitions/80.html
• MITRE ATT&CK T1059.007: https://attack.mitre.org/techniques/T1059/007/
• No known threat actor campaigns or exploit-in-the-wild evidence at this time.