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HIGH

CVE-2026-15076

CVSS v3

7.5

HIGH

EPSS Score

0.2 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-15076 Red Hat Product Security15 products fixed · 15 known affected

    io.vertx/vertx-web: Eclipse Vert.x Web Client: Information disclosure via improper cookie domain validation

    openshift-serverless-1/kn-eventing-integrations-aws-ddb-streams-source-rhel9 as a component of OpenShift Serverless · openshift-serverless-1/kn-eventing-integrations-aws-s3-sink-rhel9 as a component of OpenShift Serverless · openshift-serverless-1/kn-eventing-integrations-aws-s3-source-rhel9 as a component of OpenShift Serverless

  • RHSA-2026:68333 Red Hat Product Security6 products fixed

    Red Hat Security Advisory: Red Hat build of Cryostat security update

  • RHSA-2026:62260 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: Red Hat OpenShift Dev Spaces 3.30.0 Release.

  • RHSA-2026:54622 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Build of Apache Camel 4.18.3 for Spring Boot release.

  • RHSA-2026:54435 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Streams for Apache Kafka 3.2.1 release and security update

  • RHSA-2026:48118 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Build of Apache Camel 4.18.3 for Quarkus 3.33 update is now available (RHBQ 3.33.2.SP3)

2 more advisories

Full record on NVD

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.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published
2026-07-14
Last Modified
2026-07-14

Frequently asked questions

What is CVE-2026-15076?

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.

Is CVE-2026-15076 actively exploited?

Active exploitation of CVE-2026-15076 has not been confirmed. Its EPSS score was 0.2% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-15076?

CVE-2026-15076 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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