{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-75804", "assignerOrgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5", "state": "PUBLISHED", "assignerShortName": "openssl", "dateReserved": "2026-08-18T09:34:32.659Z", "datePublished": "2026-09-29T15:32:19.335Z", "dateUpdated": "2026-09-29T15:32:19.335Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "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"}]}], "credits": [{"lang": "en", "type": "reporter", "value": "Moltenbit"}, {"lang": "en", "type": "reporter", "value": "Bhabani Sankar Das"}, {"lang": "en", "type": "reporter", "value": "Saiyowa Security Team"}, {"lang": "en", "type": "remediation developer", "value": "Alexandr Nedvedicky"}], "datePublic": "2026-09-29T14:21:57.000Z", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Issue summary: OpenSSL QUIC stack does not enforce connection<br>level flow control for streams. Remote peers may send more bytes<br>as long as they fit within the stream flow control limits.<br><br>Impact summary: A malicious remote peer may exploit the lack of connection<br>flow control for streams to make the QUIC stack receive ~100MB of memory<br>instead of 768 KiB (default flow control window size).<br><br>CWE: CWE-770: Allocation of Resources Without Limits or Throttling<br><br>Description: The local QUIC stack advertises two flow control limits<br>to its remote peer: stream flow control limit and connection flow<br>control limit. The remote peer must follow both limits when transmitting<br>stream data.<br><br>Whenever the local QUIC stack receives a stream frame, it validates<br>that the size of the received stream frame stays within flow control limits.<br>If either limit is exceeded (stream level or connection level), then<br>the QUIC stack must close the connection with a flow control error.<br><br>The vulnerable OpenSSL QUIC stack enforces the stream-level but not<br>the connection-level limit. To exploit the issue, three conditions must be met:<br> - the remote peer opens several streams<br> - each stream must stay within the stream-level flow control limit<br> - there must be no zero-offset byte sent on any of the streams<br> (to prevent the vulnerable QUIC stack from consuming data).<br>By meeting the conditions above, the remote peer may make the local stack<br>allocate 2 x MAX_STREAMS x (stream flow control limit) bytes<br>of memory. MAX_STREAMS defaults to 100, and the limit applies to both<br>bidirectional and unidirectional streams, making it 200 in total. The default<br>flow control window for a stream is 512kB. The remote peer may<br>force the vulnerable QUIC stack to allocate 100MB of heap per connection.<br><br>FIPS impact: no<br>The FIPS module is not affected as the QUIC implementation is outside of<br>the OpenSSL FIPS module boundary."}], "value": "Issue summary: OpenSSL QUIC stack does not enforce connection\nlevel flow control for streams. Remote peers may send more bytes\nas long as they fit within the stream flow control limits.\n\nImpact summary: A malicious remote peer may exploit the lack of connection\nflow control for streams to make the QUIC stack receive ~100MB of memory\ninstead of 768 KiB (default flow control window size).\n\nCWE: CWE-770: Allocation of Resources Without Limits or Throttling\n\nDescription: The local QUIC stack advertises two flow control limits\nto its remote peer: stream flow control limit and connection flow\ncontrol limit. The remote peer must follow both limits when transmitting\nstream data.\n\nWhenever the local QUIC stack receives a stream frame, it validates\nthat the size of the received stream frame stays within flow control limits.\nIf either limit is exceeded (stream level or connection level), then\nthe QUIC stack must close the connection with a flow control error.\n\nThe vulnerable OpenSSL QUIC stack enforces the stream-level but not\nthe connection-level limit. To exploit the issue, three conditions must be met:\n - the remote peer opens several streams\n - each stream must stay within the stream-level flow control limit\n - there must be no zero-offset byte sent on any of the streams\n (to prevent the vulnerable QUIC stack from consuming data).\nBy meeting the conditions above, the remote peer may make the local stack\nallocate 2 x MAX_STREAMS x (stream flow control limit) bytes\nof memory. MAX_STREAMS defaults to 100, and the limit applies to both\nbidirectional and unidirectional streams, making it 200 in total. The default\nflow control window for a stream is 512kB. The remote peer may\nforce the vulnerable QUIC stack to allocate 100MB of heap per connection.\n\nFIPS impact: no\nThe FIPS module is not affected as the QUIC implementation is outside of\nthe OpenSSL 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": "2026-09-29T15:32:19.335Z"}, "references": [{"name": "OpenSSL Advisory", "tags": ["vendor-advisory"], "url": "https://openssl-library.org/news/secadv/20260929.txt"}, {"name": "4.0.3 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/64d3102fb5b54311e92517f26ba00169d719e74a"}, {"name": "3.6.5 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/2e8f54666b3fb7b05ff5f58aa6cac9285163654e"}, {"name": "3.5.9 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/4533ee8a5686c953ed3b644738ac4bdf20806538"}, {"name": "3.4.8 git commit", "tags": ["patch"], "url": "https://github.com/openssl/openssl/commit/f9eaecf5bdd6692da052bc65b0332af2a938ac03"}], "source": {"discovery": "UNKNOWN"}, "title": "QUIC Connection-Level Flow Control is Not Enforced for Streams", "x_generator": {"engine": "Vulnogram 0.2.0"}}}}

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