--- id: CVE-2026-11525 title: >- undici: undici: Weakening of cookie SameSite policy due to incorrect parsing of Set-Cookie header (CVE-2026-11525) summary: >- A flaw was found in undici. When undici processes Set-Cookie headers, it incorrectly interprets the SameSite attribute, accepting partial matches instead of exact ones. This allows a malicious server to downgrade a cookie's SameSite policy… severity: low cvss: 3.7 cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N' cvssSource: vendor cwe: - CWE-1286 - CWE-183 vendor: Red Hat product: Red Hat Enterprise Linux AppStream (v. 8) affected: - cryostat 4 - openshift_pipelines - amq_broker 7 - build_of_podman_desktop - developer_hub - enterprise_linux 8 - hardened_images - openshift_ai_rhoai - openshift_container_platform 4 - openshift_dev_spaces - self_service_automation_portal 2 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_8 - enterprise_linux_appstream_v_9 - openshift_data_foundation 4.18 patched: - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_8 - enterprise_linux_appstream_v_9 - hardened_images - openshift_data_foundation 4.18 published: '2026-06-17' updated: '2026-10-01' sourceUpdated: '2026-10-01T18:24:05+00:00' source: CSAF sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11525.json' references: - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11525.json - url: 'https://access.redhat.com/security/cve/CVE-2026-11525' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2490008' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-11525' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-11525' - url: 'https://cna.openjsf.org/security-advisories.html' - url: 'https://github.com/nodejs/undici/security/advisories/GHSA-g8m3-5g58-fq7m' - url: 'https://access.redhat.com/errata/RHSA-2026:35842' - url: 'https://access.redhat.com/errata/RHSA-2026:35841' - url: 'https://access.redhat.com/errata/RHSA-2026:41947' - url: 'https://access.redhat.com/errata/RHSA-2026:39868' - url: 'https://access.redhat.com/errata/RHSA-2026:35892' - url: 'https://access.redhat.com/errata/RHSA-2026:35891' - url: 'https://access.redhat.com/errata/RHSA-2026:38236' - url: 'https://access.redhat.com/errata/RHSA-2026:45783' - url: 'https://access.redhat.com/errata/RHSA-2026:56431' - url: 'https://github.com/advisories/GHSA-g8m3-5g58-fq7m' tags: - csaf - vex - red-hat - ghsa - npm epss: 0.00238 epssPercentile: 0.14827 ecosystem: npm ingestedAt: '2026-06-22T15:59:08.194Z' --- ## Overview A flaw was found in undici. When undici processes Set-Cookie headers, it incorrectly interprets the SameSite attribute, accepting partial matches instead of exact ones. This allows a malicious server to downgrade a cookie's SameSite policy to a less secure setting, potentially leading to unintended information disclosure or a weakening of security protections for the user. ## Vendor advisories - **RHSA-2026:35842** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-07-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:35842) - **RHSA-2026:35841** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-07-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:35841) - **RHSA-2026:41947** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-07-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:41947) - **RHSA-2026:39868** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-07-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:39868) - **RHSA-2026:35892** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-07-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:35892) - **RHSA-2026:35891** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-07-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:35891) - **RHSA-2026:38236** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:38236) - **RHSA-2026:45783** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:45783) - **RHSA-2026:56431** · Red Hat · fixed in: Red Hat Openshift Data Foundation 4.18 · released 2026-08-18 · [advisory](https://access.redhat.com/errata/RHSA-2026:56431) - **Red Hat VEX** · Low · affected: Cryostat 4, OpenShift Pipelines, Red Hat AMQ Broker 7, Red Hat Build of Podman Desktop, Red Hat Developer Hub, Red Hat Enterprise Linux 8, … · no fix planned: Cryostat 4, OpenShift Pipelines, Red Hat AMQ Broker 7, Red Hat Build of Podman Desktop, … · updated 2026-10-01 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11525.json) **undici: undici: Weakening of cookie SameSite policy due to incorrect parsing of Set-Cookie header** — rated Low by Red Hat. Released 2026-06-17, updated 2026-10-01. Affected: - Cryostat 4 - OpenShift Pipelines - Red Hat AMQ Broker 7 - Red Hat Build of Podman Desktop - Red Hat Developer Hub - Red Hat Enterprise Linux 8 - Red Hat Hardened Images - Red Hat OpenShift AI (RHOAI) - Red Hat OpenShift Container Platform 4 - Red Hat OpenShift Dev Spaces - Self-service automation portal 2 Fixed: - Red Hat Enterprise Linux AppStream (v. 10) - Red Hat Enterprise Linux AppStream (v. 8) - Red Hat Enterprise Linux AppStream (v. 9) - Red Hat Hardened Images - Red Hat Openshift Data Foundation 4.18 No fix planned: - Cryostat 4 - OpenShift Pipelines - Red Hat AMQ Broker 7 - Red Hat Build of Podman Desktop - Red Hat Developer Hub - Red Hat Enterprise Linux 8 - Red Hat Hardened Images - Red Hat OpenShift AI (RHOAI) - Red Hat OpenShift Container Platform 4 - Red Hat OpenShift Dev Spaces - Self-service automation portal 2 Not affected: - Red Hat Openshift Data Foundation 4.18 - Red Hat Hardened Images ## Remediation For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:35842 For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:35841 For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:41947 Workarounds / mitigations: - 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. ## Package advisory (CVE-2026-11525) Affected packages: - `undici < 6.27.0` - `undici >= 7.0.0, < 7.28.0` - `undici >= 8.0.0, < 8.5.0` Patched in: - `undici 6.27.0` - `undici 7.28.0` - `undici 8.5.0` Source: https://github.com/advisories/GHSA-g8m3-5g58-fq7m