CVE-2026-15076
Received
Received - Intake
Cross-Site Cookie Injection in Eclipse Vert.x Web Client
Vulnerability report for CVE-2026-15076, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-14
Last updated on: 2026-07-14
Assigner: Eclipse Foundation
Description
Description
In versions up to and including 4.5.29 (4.x branch) and 5.1.4 (5.x branch), the WebClientSession component of Eclipse Vert.x Web Client does not validate that the Domain attribute of a Set-Cookie response header matches the originating server's domain, in violation of RFC 6265 section 5.3.
An attacker who controls any server that the victim application contacts can inject a cookie scoped to an arbitrary third-party domain; because the session store performs no cross-domain ownership check, it stores and later transmits that cookie to the targeted domain.
When the victim application subsequently sends a request to the targeted domain using the same WebClientSession, it presents the attacker-injected cookie, causing the receiving service to process the request under the attacker's account. Sensitive data included in the victim application's requests, such as payment amounts, card details, or other API payloads, may then be accessible to the attacker through their own account on that service.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| eclipse | vert.x_web_client | to 4.5.29|end_including=5.1.4 (inc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-346 | The product does not properly verify that the source of data or communication is valid. |
