CVE-2025-27156 Overview
CVE-2025-27156 is a stored cross-site scripting (XSS) vulnerability in Tuleap, an open source suite for managing software development and collaboration. The mass emailing feature fails to sanitize HTML content before delivery to recipients. An authenticated user with mass emailing privileges can inject arbitrary HTML or script payloads into outbound messages. Recipients rendering the message in vulnerable clients may be exposed to phishing content or client-side exploitation. The issue is tracked under [CWE-79] and is fixed in Tuleap Community Edition 16.4.99.1740567344, Tuleap Enterprise Edition 16.4-6, and Tuleap Enterprise Edition 16.3-11.
Critical Impact
Attackers with mass emailing access can deliver malicious HTML to every recipient, enabling phishing campaigns and indirect exploitation of mail client vulnerabilities.
Affected Products
- Enalean Tuleap Community Edition prior to 16.4.99.1740567344
- Enalean Tuleap Enterprise Edition prior to 16.4-6
- Enalean Tuleap Enterprise Edition prior to 16.3-11
Discovery Timeline
- 2025-03-04 - CVE-2025-27156 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-27156
Vulnerability Analysis
The vulnerability resides in Tuleap's mass emailing feature. The component accepts user-supplied content and embeds it directly into HTML email bodies without applying output encoding or HTML sanitization. Any script tags, event handlers, or crafted markup submitted by the sender pass through to recipients. Because delivery occurs over the network with only low privileges and requires user interaction on the recipient side, exploitation scales with the size of the target mailing list. The scope change reflects that the payload executes in the trust context of the recipient's mail client rather than the Tuleap application.
Root Cause
The root cause is missing input sanitization and output encoding on HTML content generated by the mass emailing workflow. Tuleap treats sender-provided HTML as trusted markup and forwards it verbatim into the outbound message body. This falls under [CWE-79] (Improper Neutralization of Input During Web Page Generation).
Attack Vector
An authenticated user with permission to send mass emails composes a message containing malicious HTML or JavaScript. When recipients open the message in an HTML-rendering mail client, the injected payload executes. Attackers can craft convincing phishing lures, harvest credentials through fake login forms, or chain the primitive with known mail client vulnerabilities. Refer to the Tuleap GitHub Security Advisory GHSA-x2v2-xr59-c9cf for the technical write-up. No public proof-of-concept code has been released for this issue.
Detection Methods for CVE-2025-27156
Indicators of Compromise
- Outbound emails from Tuleap containing <script> tags, inline event handlers such as onerror or onclick, or unexpected external resource references.
- Recipient reports of unexpected redirects, credential prompts, or rendering anomalies from Tuleap-originated mail.
- Audit log entries showing large mass email jobs initiated by low-privileged accounts.
Detection Strategies
- Inspect the Tuleap mass emailing audit trail for messages authored by accounts that do not routinely send bulk communications.
- Review outbound mail gateway logs for Tuleap-originated messages that fail HTML content policy checks.
- Compare running Tuleap versions against the patched releases 16.4.99.1740567344, 16.4-6, and 16.3-11.
Monitoring Recommendations
- Enable content inspection on the mail gateway to flag scripts and suspicious HTML in outbound Tuleap traffic.
- Alert on privilege changes that grant mass emailing capability to non-administrative users.
- Correlate recipient-side phishing reports with Tuleap send events using SIEM search rules.
How to Mitigate CVE-2025-27156
Immediate Actions Required
- Upgrade Tuleap Community Edition to 16.4.99.1740567344 or later.
- Upgrade Tuleap Enterprise Edition to 16.4-6 or 16.3-11 depending on the deployed branch.
- Audit accounts holding mass emailing privileges and revoke access from users who do not require it.
- Notify recipients who received mass emails during the exposure window and instruct them to report suspicious content.
Patch Information
Enalean released the fix in commit a0bc657297b405debce1f5bcbbb30c733f3f09bd. Tracking details are available in the Tuleap tracker entry 42177. Administrators should apply the upgrade following the standard Tuleap update procedure and validate the running version after deployment.
Workarounds
- Restrict the mass emailing permission to a small set of trusted administrators until the patch is applied.
- Configure the upstream mail gateway to strip active HTML content such as <script> blocks and inline event handlers from Tuleap-originated messages.
- Advise recipients to view mail from Tuleap in plain-text mode where feasible during the interim period.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
