{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-12708", "assignerOrgId": "a22f1246-ba21-4bb4-a601-ad51614c1513", "state": "PUBLISHED", "assignerShortName": "cloudflare", "dateReserved": "2026-06-19T10:44:16.225Z", "datePublished": "2026-11-10T13:25:09.558Z", "dateUpdated": "2026-11-10T13:42:52.186Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "a22f1246-ba21-4bb4-a601-ad51614c1513", "shortName": "cloudflare", "dateUpdated": "2026-11-10T13:42:52.186Z"}, "title": "Unbounded HTTP/3 Datagram flow map growth in tokio-quiche", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-401", "description": "CWE-401 Missing release of memory after effective lifetime", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-130", "descriptions": [{"lang": "en", "value": "CAPEC-130 Excessive Allocation"}]}], "affected": [{"vendor": "Cloudflare", "product": "tokio-quiche", "repo": "https://github.com/cloudflare/quiche/tree/master/tokio-quiche", "versions": [{"status": "affected", "version": "0.0.1", "lessThanOrEqual": "0.20.1", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "Summary\n\n\nCloudflare tokio-quiche was found to contain an uncontrolled resource consumption vulnerability in its HTTP/3 DATAGRAM handling. For every previously unseen flow identifier (quarter stream ID) received in a DATAGRAM frame, tokio-quiche creates and retains new, per-flow state. A remote peer can send DATAGRAMs with many distinct identifiers, causing the per-connection flow map and associated channel state to grow without bound.\n\nImpact\n\n\nExploitation can exhaust process memory and cause a denial of service. The vulnerable code is used in both client and server configurations, so either role can be affected by a malicious peer. QUIC DATAGRAM support in tokio-quiche is enabled by default through QuicSettings::enable_dgram; applications can disable it by setting this field to false. The vulnerable HTTP/3 path is reachable only when DATAGRAM support is negotiated with the peer. Core quiche and HTTP/3 deployments without DATAGRAM support are not affected.\u00a0\n\n\n\n\n\n\nMitigation\n\n\nDisable DATAGRAMs in tokio-quiche\u2019s QuicSettings::enable_dgram.\n\n\n\n\n\n\nRemediation\n\n\nUpgrade to tokio-quiche version 0.23.0 or later. The fixed code creates flow state only for valid DATAGRAM-capable request streams, which are bounded by QUIC\u2019s stream limits. To tolerate packet reordering, servers retain early DATAGRAMs in a bounded, expiring buffer, while clients discard DATAGRAMs for unknown flows.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<h2><b>Summary</b></h2><p><b><br></b><span>Cloudflare tokio-quiche was found to contain an uncontrolled resource consumption vulnerability in its HTTP/3 DATAGRAM handling. For every previously unseen flow identifier (quarter stream ID) received in a DATAGRAM frame, tokio-quiche creates and retains new, per-flow state. A remote peer can send DATAGRAMs with many distinct identifiers, causing the per-connection flow map and associated channel state to grow without bound.</span></p><h2><b>Impact</b></h2><p><b><br></b><span>Exploitation can exhaust process memory and cause a denial of service. The vulnerable code is used in both client and server configurations, so either role can be affected by a malicious peer. QUIC DATAGRAM support in tokio-quiche is enabled by default through </span><span>QuicSettings::enable_dgram</span><span>; applications can disable it by setting this field to </span><span>false</span><span>. The vulnerable HTTP/3 path is reachable only when DATAGRAM support is negotiated with the peer. Core quiche and HTTP/3 deployments without DATAGRAM support are not affected.&nbsp;</span></p><p><span><br></span></p><h2><b>Mitigation</b></h2><p><b><br></b><span>Disable DATAGRAMs in tokio-quiche\u2019s </span><span>QuicSettings::enable_dgram</span><span>.</span></p><p><b><br></b></p><h2><b>Remediation</b></h2><p><b><br></b><span>Upgrade to tokio-quiche version 0.23.0 or later. The fixed code creates flow state only for valid DATAGRAM-capable request streams, which are bounded by QUIC\u2019s stream limits. To tolerate packet reordering, servers retain early DATAGRAMs in a bounded, expiring buffer, while clients discard DATAGRAMs for unknown flows.</span></p><br>"}]}], "references": [{"url": "https://www.cve.org/CVERecord?id=CVE-2026-12708"}, {"url": "https://github.com/cloudflare/quiche/security/advisories/GHSA-wcm9-jv39-r963"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 8.7, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}}], "source": {"discovery": "UNKNOWN"}, "x_generator": {"engine": "Vulnogram 1.0.5"}}}}

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