{"id":"GHSA-36w4-95hv-5vwg","summary":"gun_http2 has an Origin Validation Error vulnerability","details":"Origin Validation Error vulnerability in ninenines gun (gun_http2 module) allows cross-origin cookie injection via unvalidated HTTP/2 PUSH_PROMISE authority.\n\nIn gun_http2:push_promise_frame/7, the :authority pseudo-header from an incoming PUSH_PROMISE frame is stored verbatim into the promised stream record without checking that it matches the connection's origin. When gun_http2:headers_frame/9 later processes the response headers for the promised stream, it calls gun_cookies:set_cookie_header/7 with the unvalidated server-supplied authority before any status branching and before user code can act. This violates RFC 7540 §10.6 / RFC 9113 §8.4, which require receivers to treat as a protocol error any push for a resource the server is not authoritative for.\n\nA malicious or compromised HTTP/2 server can plant cookies scoped to arbitrary third-party domains into the client's shared cookie store. This enables session fixation attacks against those domains and, if the planted cookie overrides a legitimate session token, may result in account takeover. No user interaction beyond making a normal HTTP/2 request to the attacker-controlled server is required.\n\nThis issue affects gun: from 2.0.0 before 2.4.0.","aliases":["CVE-2026-43972","EEF-CVE-2026-43972"],"modified":"2026-07-29T16:11:28.990995927Z","published":"2026-06-08T15:32:59Z","database_specific":{"github_reviewed_at":"2026-07-29T15:44:30Z","nvd_published_at":"2026-06-08T15:16:46Z","cwe_ids":["CWE-346"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43972"},{"type":"WEB","url":"https://github.com/ninenines/gun/commit/567863ff53802fed21c3b3f25812db7f7ae29676"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-43972.html"},{"type":"PACKAGE","url":"https://github.com/ninenines/gun"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-43972"}],"affected":[{"package":{"name":"gun","ecosystem":"Hex","purl":"pkg:hex/gun"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.0"},{"fixed":"2.4.0"}]}],"versions":["2.0.0","2.0.1","2.1.0","2.2.0","2.3.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-36w4-95hv-5vwg/GHSA-36w4-95hv-5vwg.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N"}]}