{"id":"CVE-2026-63075","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-63075","summary":"Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly\nsends ack-eliciting packets while not acknowledging ACK-only responses, the\nQUIC stack can retain ACK-only…","details":"Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly\nsends ack-eliciting packets while not acknowledging ACK-only responses, the\nQUIC stack can retain ACK-only packet metadata for the lifetime of the\nconnection.\n\nImpact summary: A remote peer that can complete a QUIC handshake can\ncause connection-scoped memory growth which may lead to Denial of Service\nthrough memory exhaustion, especially with sustained traffic or many concurrent\nQUIC connections.\n\nCWE: CWE-770: Allocation of Resources Without Limits or Throttling\n\nDescription: When the OpenSSL QUIC stack sends an ACK-only packet,\nthere is no requirement by the QUIC protocol that the peer will acknowledge\nthat ACK-only packet (i.e. it is itself not ack-eliciting). However, the OpenSSL\nimplementation stores the metadata about the ACK frames regardless.\nIn and of itself that's ok, but if a malicious peer establishes a connection, and\nthen drives the connection such that ACK-only packets are forced from the \nOpenSSL implementation peer (i.e., by sending numerous PING frames),\nand then withholding any subsequent acks for ack-eliciting data, like\nlegitimate data, said malicious peer can force inappropriate memory growth\non the OpenSSL peer, potentially leading to a Denial of Service.\n\nThe fix is to ensure that we account for the transmission of the ACK-only\npacket in the packet histories high and low watermark without actually storing\nthe ACK-only packet metadata itself.\n\nFIPS impact: no\nThe OpenSSL FIPS module is not affected as the QUIC code is\noutside the FIPS module boundary.","published":"2026-08-25T13:19:26.413","modified":"2026-08-25T13:19:26.413","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/openssl/openssl/commit/7308946576b12e64b8be53bcf0a120354b2b42bc","label":"openssl/openssl@7308946"},"references":[{"type":"WEB","url":"https://github.com/openssl/openssl/commit/7308946576b12e64b8be53bcf0a120354b2b42bc"},{"type":"WEB","url":"https://github.com/openssl/openssl/commit/7c98d79738549df92868e7dd9be4bbf061eed709"},{"type":"WEB","url":"https://github.com/openssl/openssl/commit/bf84721c2548351176e367e6de505792f0118dc6"},{"type":"WEB","url":"https://github.com/openssl/openssl/commit/c902e5f16d6a9e130e96d3ca6d8f64d71652e393"},{"type":"WEB","url":"https://openssl-library.org/news/secadv/20260825.txt"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-08-25T13:19:26.413"}}