CVE-2026-15076
Description
A flaw was found in Eclipse Vert.x Web Client. The WebClientSession component does not properly validate the Domain attribute of a Set-Cookie response header against the originating server's domain. This vulnerability allows a remote attacker to inject a cookie scoped to an arbitrary third-party domain. When the victim application subsequently sends a request to the targeted domain, the injected cookie is presented, potentially leading to information disclosure and unauthorized access to sensitive data through the attacker's account on that service.
Statement
This is an Important information disclosure flaw in Eclipse Vert.x Web Client's WebClientSession component. The vulnerability arises from insufficient validation of the Domain attribute in Set-Cookie response headers, allowing a remote attacker to inject cookies scoped to arbitrary third-party domains. This could lead to sensitive data exposure and unauthorized access if a victim application subsequently sends requests to the targeted domain, presenting the attacker-controlled cookie. The impact is significant as it bypasses expected cross-domain security boundaries.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Access Control,Other
Technical Impact: Gain Privileges or Assume Identity; Varies by Context
An attacker can access any functionality that is inadvertently accessible to the source.
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