The vulnerability is exploitable only when gun is configured with a cookie_store and connects to an HTTP/2 server with server push enabled.
" } ], "value": "The vulnerability is exploitable only when gun is configured with a cookie_store and connects to an HTTP/2 server with server push enabled." } ], "cpeApplicability": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.4.0", "versionStartIncluding": "2.0.0", "vulnerable": true } ], "negate": false, "operator": "OR" } ], "operator": "AND" } ], "credits": [ { "lang": "en", "type": "finder", "value": "Peter Ullrich" }, { "lang": "en", "type": "remediation developer", "value": "Loïc Hoguin" } ], "descriptions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "Origin Validation Error vulnerability in ninenines gun (gun_http2 module) allows cross-origin cookie injection via unvalidated HTTP/2 PUSH_PROMISE authority.In 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.
A 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.
This issue affects gun: from 2.0.0 before 2.4.0.
" } ], "value": "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." } ], "impacts": [ { "capecId": "CAPEC-61", "descriptions": [ { "lang": "en", "value": "CAPEC-61 Session Fixation" } ] } ], "metrics": [ { "cvssV4_0": { "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 6.3, "baseSeverity": "MEDIUM", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "vectorString": "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW" }, "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ] } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-346", "description": "CWE-346 Origin Validation Error", "lang": "en", "type": "CWE" } ] } ], "providerMetadata": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-06-08T16:34:45.350Z" }, "references": [ { "tags": [ "related", "third-party-advisory" ], "url": "https://cna.erlef.org/cves/CVE-2026-43972.html" }, { "tags": [ "related" ], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-43972" }, { "tags": [ "patch" ], "url": "https://github.com/ninenines/gun/commit/567863ff53802fed21c3b3f25812db7f7ae29676" } ], "source": { "discovery": "EXTERNAL" }, "title": "gun HTTP/2 PUSH_PROMISE authority not validated against connection origin allows cross-origin cookie injection", "x_generator": { "engine": "cvelib 1.8.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-06-08T15:42:59.352280Z", "id": "CVE-2026-43972", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-08T15:43:06.577Z" } } ] } }