{"cve":{"cve_id":"CVE-2026-11525","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00248,"epss_percentile":0.15771,"epss_as_of":"2026-06-23","description":"Impact:\nWhen undici parses a Set-Cookie header, it accepts any SameSite attribute value that contains Strict, Lax, or None as a substring, rather than the case-insensitive exact match specified by RFC 6265. Non-spec values are silently mapped to one of the three standard tokens. For example, SameSite=NoneOfYourBusiness is parsed as None (the most permissive setting), and SameSite=StrictLax is parsed as Lax (a downgrade from Strict).\n\nAffected applications are those that consume Set-Cookie headers from server responses (for example via undici's fetch or proxy code paths) and then forward or rely on the parsed sameSite attribute. A malicious or non-compliant server can coerce the consumer's view of a cookie's SameSite policy to a weaker value, silently degrading the SameSite enforcement the cookie is supposed to provide.\n\nThis was introduced in undici 5.15.0 when the cookies feature was added.\n\nPatches:\nUpgrade to undici v6.26.0, v7.28.0 or v8.5.0.\n\nWorkarounds:\nAfter parsing a Set-Cookie header, validate that the resulting sameSite attribute is one of 'Strict', 'Lax', or 'None' (exact, case-insensitive) before forwarding or relying on it.","published_at":"2026-06-17T17:31:03.163000Z","last_modified_at":null,"cvss_v3_score":3.7,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","cvss_v3_severity":"LOW","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-183"],"nvd_references":["https://github.com/nodejs/undici/security/advisories/GHSA-g8m3-5g58-fq7m","https://cna.openjsf.org/security-advisories.html"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:28:55.210969Z"},"effective_severity":"LOW","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"H","value_label":"High"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"N","value_label":"None"},{"metric":"I","name":"Integrity","value":"L","value_label":"Low"},{"metric":"A","name":"Availability","value":"N","value_label":"None"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"undici","vendor_name":"undici","product_slug":"undici","product_name":"undici","version_start":"0","version_start_inclusive":true,"version_end":"6.26.0","version_end_inclusive":false,"cpe23_uri":"cve5:undici:undici:0:6.26.0"},{"vendor_slug":"undici","vendor_name":"undici","product_slug":"undici","product_name":"undici","version_start":"6.26.0","version_start_inclusive":true,"version_end":"6.26.0","version_end_inclusive":true,"cpe23_uri":"cve5:undici:undici:6.26.0:6.26.0"},{"vendor_slug":"undici","vendor_name":"undici","product_slug":"undici","product_name":"undici","version_start":"7.0.0","version_start_inclusive":true,"version_end":"7.28.0","version_end_inclusive":false,"cpe23_uri":"cve5:undici:undici:7.0.0:7.28.0"},{"vendor_slug":"undici","vendor_name":"undici","product_slug":"undici","product_name":"undici","version_start":"7.28.0","version_start_inclusive":true,"version_end":"7.28.0","version_end_inclusive":true,"cpe23_uri":"cve5:undici:undici:7.28.0:7.28.0"},{"vendor_slug":"undici","vendor_name":"undici","product_slug":"undici","product_name":"undici","version_start":"8.0.0","version_start_inclusive":true,"version_end":"8.5.0","version_end_inclusive":false,"cpe23_uri":"cve5:undici:undici:8.0.0:8.5.0"},{"vendor_slug":"undici","vendor_name":"undici","product_slug":"undici","product_name":"undici","version_start":"8.5.0","version_start_inclusive":true,"version_end":"8.5.0","version_end_inclusive":true,"cpe23_uri":"cve5:undici:undici:8.5.0:8.5.0"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-g8m3-5g58-fq7m","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://cna.openjsf.org/security-advisories.html","source_type":"VENDOR_ADVISORY","tags":["advisory"]}],"timeline":[{"type":"published","at":"2026-06-17T17:31:03.163000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:50:40.391234Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:50:40.391234Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:50:40.391234Z","label":"CVSS score revised","source":"cvelistv5"}]}