{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63075", "assignerOrgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5", "state": "PUBLISHED", "assignerShortName": "openssl", "dateReserved": "2026-07-15T13:10:26.188Z", "datePublished": "2026-08-25T13:00:04.752Z", "dateUpdated": "2026-08-25T14:36:51.928Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "OpenSSL", "vendor": "OpenSSL", "versions": [{"lessThan": "4.0.2", "status": "affected", "version": "4.0.0", "versionType": "semver"}, {"lessThan": "3.6.4", "status": "affected", "version": "3.6.0", "versionType": "semver"}, {"lessThan": "3.5.8", "status": "affected", "version": "3.5.0", "versionType": "semver"}, {"lessThan": "3.4.7", "status": "affected", "version": "3.4.0", "versionType": "semver"}]}], "credits": [{"lang": "en", "type": "reporter", "value": "Opal Wright (Trail of Bits)"}, {"lang": "en", "type": "remediation developer", "value": "Neil Horman"}], "datePublic": "2026-08-25T11:36:16.000Z", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly<br>sends ack-eliciting packets while not acknowledging ACK-only responses, the<br>QUIC stack can retain ACK-only packet metadata for the lifetime of the<br>connection.<br><br>Impact summary: A remote peer that can complete a QUIC handshake can<br>cause connection-scoped memory growth which may lead to Denial of Service<br>through memory exhaustion, especially with sustained traffic or many concurrent<br>QUIC connections.<br><br>CWE: CWE-770: Allocation of Resources Without Limits or Throttling<br><br>Description: When the OpenSSL QUIC stack sends an ACK-only packet,<br>there is no requirement by the QUIC protocol that the peer will acknowledge<br>that ACK-only packet (i.e. it is itself not ack-eliciting). However, the OpenSSL<br>implementation stores the metadata about the ACK frames regardless.<br>In and of itself that's ok, but if a malicious peer establishes a connection, and<br>then drives the connection such that ACK-only packets are forced from the <br>OpenSSL implementation peer (i.e., by sending numerous PING frames),<br>and then withholding any subsequent acks for ack-eliciting data, like<br>legitimate data, said malicious peer can force inappropriate memory growth<br>on the OpenSSL peer, potentially leading to a Denial of Service.<br><br>The fix is to ensure that we account for the transmission of the ACK-only<br>packet in the packet histories high and low watermark without actually storing<br>the ACK-only packet metadata itself.<br><br>FIPS impact: no<br>The OpenSSL FIPS module is not affected as the QUIC code is<br>outside the FIPS module boundary."}], "value": "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."}], "metrics": [{"format": "other", "other": {"content": {"text": "Low"}, "type": "https://openssl-library.org/policies/general/security-policy/"}}], "problemTypes": [{"descriptions": [{"cweId": "CWE-770", "description": "CWE-770 Allocation of Resources Without Limits or Throttling", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5", "shortName": "openssl", "dateUpdated": "2026-08-25T13:00:04.752Z"}, "references": [{"name": "OpenSSL Advisory", "tags": ["vendor-advisory"], "url": "https://openssl-library.org/news/secadv/20260825.txt"}, {"name": "4.0.2 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/7308946576b12e64b8be53bcf0a120354b2b42bc"}, {"name": "3.6.4 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/bf84721c2548351176e367e6de505792f0118dc6"}, {"name": "3.5.8 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/7c98d79738549df92868e7dd9be4bbf061eed709"}, {"name": "3.4.7 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/c902e5f16d6a9e130e96d3ca6d8f64d71652e393"}], "source": {"discovery": "UNKNOWN"}, "title": "QUIC ACK-only Packet Retention Can Cause Memory Exhaustion", "x_generator": {"engine": "Vulnogram 0.2.0"}}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-08-25T14:36:48.832724Z", "id": "CVE-2026-63075", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"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": "2026-08-25T14:36:51.928Z"}}]}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "OpenSSL", "vendor": "OpenSSL", "versions": [{"lessThan": "4.0.2", "status": "affected", "version": "4.0.0", "versionType": "semver"}, {"lessThan": "3.6.4", "status": "affected", "version": "3.6.0", "versionType": "semver"}, {"lessThan": "3.5.8", "status": "affected", "version": "3.5.0", "versionType": "semver"}, {"lessThan": "3.4.7", "status": "affected", "version": "3.4.0", "versionType": "semver"}]}], "source": "openssl-security@openssl.org"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-63075", "lastModified": "2026-08-25T13:19:26.413", "metrics": {}, "published": "2026-08-25T13:19:26.413", "references": [{"source": "openssl-security@openssl.org", "url": "https://github.com/openssl/openssl/commit/7308946576b12e64b8be53bcf0a120354b2b42bc"}, {"source": "openssl-security@openssl.org", "url": "https://github.com/openssl/openssl/commit/7c98d79738549df92868e7dd9be4bbf061eed709"}, {"source": "openssl-security@openssl.org", "url": "https://github.com/openssl/openssl/commit/bf84721c2548351176e367e6de505792f0118dc6"}, {"source": "openssl-security@openssl.org", "url": "https://github.com/openssl/openssl/commit/c902e5f16d6a9e130e96d3ca6d8f64d71652e393"}, {"source": "openssl-security@openssl.org", "url": "https://openssl-library.org/news/secadv/20260825.txt"}], "sourceIdentifier": "openssl-security@openssl.org", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "openssl-security@openssl.org", "type": "Secondary"}]}

{}

{}