{"schema":"threatline.record/2","record":{"id":"CVE-2026-84784","aliases":[],"summary":"QUIC: Unbounded RETIRE_CONNECTION_ID Backlog","details":"Issue summary: A malicious remote peer may flood the local QUIC\nstack with NEW_CONNECTION_ID frames by avoiding a limit check on\nhow many connection IDs the remote QUIC stack can use.\n\nImpact summary: The local QUIC stack sends a RETIRE_CONN_ID frame\nfor every NEW_CONNECTION_ID frame it receives. The RETIRE_CONN_ID\nframe is dispatched via the Control Frame Queue (CFQ). If the remote\npeer also withholds ACKs, then it can force the local stack\nto allocate ~400MB (depending on ACK delay).\n\nCWE: CWE-770: Allocation of Resources Without Limits or Throttling\n\nDescription: RFC 9000 sections 5.1.1 and 5.1.2 [1] describe the mechanism\nby which a remote peer can notify the local QUIC stack to change the\ndestination connection ID (a.k.a. CID) the local stack uses to\nidentify the connection at the remote peer. Each CID is associated\nwith a sequence number. The sequence number is transmitted\nin NEW_CONNECTION_ID and RETIRE_CONNECTION_ID frames to identify the CID\nwhich is being either associated with a connection or retired.\n\nThe remote peer sends a NEW_CONNECTION_ID frame to let the local stack know\na new CID is being associated with an existing connection. The\nNEW_CONNECTION_ID frame carries the new CID, its sequence number, and the\nretire-prior-to number. The retire-prior-to identifies existing\nCIDs that are to be retired. The local QUIC stack must send a\nRETIRE_CONNECTION_ID for every destination CID whose sequence number\nis less than retire-prior-to. The CID becomes retired after the\nlocal stack receives an ACK for its RETIRE_CONNECTION_ID frame.\n\nAlthough the OpenSSL QUIC stack supports at most one destination CID\nfor every connection, it can be tricked into processing more than\none RETIRE_CONNECTION_ID frame per connection. The OpenSSL QUIC\nstack currently retires the destination CID as soon as it receives\nthe NEW_CONNECTION_ID, while in fact the destination CID must\nbe retired after an ACK for the RETIRE_CONNECTION_ID frame is received.\nCorrecting the flawed logic also fixes the backlog growth.\n\n[1] https://datatracker.ietf.org/doc/html/rfc9000#name-issuing-connection-ids\n\nFIPS impact: no\nThe FIPS module is not affected as the QUIC implementation is outside of\nthe OpenSSL FIPS module boundary.","categories":["Libraries & packages"],"product":"OpenSSL","vendor":"OpenSSL","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84784","source_modified_at":"2026-09-29T16:44:09.766Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"OpenSSL","vendor":"OpenSSL","versions":[{"lessThan":"4.0.3","status":"affected","version":"4.0.0","versionType":"semver"},{"lessThan":"3.6.5","status":"affected","version":"3.6.0","versionType":"semver"},{"lessThan":"3.5.9","status":"affected","version":"3.5.0","versionType":"semver"},{"lessThan":"3.4.8","status":"affected","version":"3.4.0","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84784","source_modified_at":"2026-09-29T16:44:09.766Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"OpenSSL","ecosystem":null},"version":"4.0.3","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84784","source_modified_at":"2026-09-29T16:44:09.766Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"OpenSSL","ecosystem":null},"version":"3.6.5","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84784","source_modified_at":"2026-09-29T16:44:09.766Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"OpenSSL","ecosystem":null},"version":"3.5.9","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84784","source_modified_at":"2026-09-29T16:44:09.766Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"OpenSSL","ecosystem":null},"version":"3.4.8","basis":"first unaffected version stated in the CVE record"}],"cvss":7.5,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00403,"percentile":0.33464,"score_date":"2026-10-23"},"published_at":"2026-09-29T15:32:25.758Z","modified_at":"2026-09-29T16:44:09.766Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-84784","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-29T16:44:09.766Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-84784","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://openssl-library.org/news/secadv/20260929.txt","tags":["vendor-advisory"]},{"source":"CVE List","url":"https://github.com/openssl/openssl/commit/e9e5155833fa968bee50024bf9ca3a185ab599fe","tags":["patch"]},{"source":"CVE List","url":"https://github.com/openssl/openssl/commit/4685c914b0d410b1034f40b547c95bc95e7a380a","tags":["patch"]},{"source":"CVE List","url":"https://github.com/openssl/openssl/commit/dba3c48d653c64fcbc9070a17a0ee2b3e2f3af1f","tags":["patch"]},{"source":"CVE List","url":"https://github.com/openssl/openssl/commit/9a30fe0fba195c14e5b87bf93c0d0fdb70373806","tags":["patch"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CISA ADP","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-09-29T16:43:47.766260Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-09-29T16:44:09.766Z","content_hash":"9eaef51c777aa540d3328b95bf2e13032b91bcf2c0a7cbbbd0e2ea3c109b9141"}}