CVE-2026-12708 (GCVE-0-2026-12708)

Vulnerability from cvelistv5 – Published: 2026-11-10 13:25 – Updated: 2026-11-10 13:42
VLAI
Title
Unbounded HTTP/3 Datagram flow map growth in tokio-quiche
Summary
Summary 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. Impact 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 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.  Mitigation Disable DATAGRAMs in tokio-quiche’s QuicSettings::enable_dgram. Remediation 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’s stream limits. To tolerate packet reordering, servers retain early DATAGRAMs in a bounded, expiring buffer, while clients discard DATAGRAMs for unknown flows.
Severity
8.7 (High)
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
CWE
  • CWE-401 - Missing release of memory after effective lifetime
Assigner
cloudflare CNA under the mitre root
CNA scorecard – unranked: 9 records in the last 180 days, 10 needed details
References
Impacted products
Vendor Product Version CPE status
Cloudflare tokio-quiche Affected: 0.0.1 , ≤ 0.20.1 (semver)
guessed Create a notification for this product.
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "tokio-quiche",
          "repo": "https://github.com/cloudflare/quiche/tree/master/tokio-quiche",
          "vendor": "Cloudflare",
          "versions": [
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              "versionType": "semver"
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              "value": "\u003ch2\u003e\u003cb\u003eSummary\u003c/b\u003e\u003c/h2\u003e\u003cp\u003e\u003cb\u003e\u003cbr\u003e\u003c/b\u003e\u003cspan\u003eCloudflare 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.\u003c/span\u003e\u003c/p\u003e\u003ch2\u003e\u003cb\u003eImpact\u003c/b\u003e\u003c/h2\u003e\u003cp\u003e\u003cb\u003e\u003cbr\u003e\u003c/b\u003e\u003cspan\u003eExploitation 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 \u003c/span\u003e\u003cspan\u003eQuicSettings::enable_dgram\u003c/span\u003e\u003cspan\u003e; applications can disable it by setting this field to \u003c/span\u003e\u003cspan\u003efalse\u003c/span\u003e\u003cspan\u003e. 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.\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan\u003e\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e\u003ch2\u003e\u003cb\u003eMitigation\u003c/b\u003e\u003c/h2\u003e\u003cp\u003e\u003cb\u003e\u003cbr\u003e\u003c/b\u003e\u003cspan\u003eDisable DATAGRAMs in tokio-quiche\u2019s \u003c/span\u003e\u003cspan\u003eQuicSettings::enable_dgram\u003c/span\u003e\u003cspan\u003e.\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003e\u003cbr\u003e\u003c/b\u003e\u003c/p\u003e\u003ch2\u003e\u003cb\u003eRemediation\u003c/b\u003e\u003c/h2\u003e\u003cp\u003e\u003cb\u003e\u003cbr\u003e\u003c/b\u003e\u003cspan\u003eUpgrade 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.\u003c/span\u003e\u003c/p\u003e\u003cbr\u003e"
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          "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."
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            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
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            "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",
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          "url": "https://www.cve.org/CVERecord?id=CVE-2026-12708"
        },
        {
          "url": "https://github.com/cloudflare/quiche/security/advisories/GHSA-wcm9-jv39-r963"
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      "source": {
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    "datePublished": "2026-11-10T13:25:09.558Z",
    "dateReserved": "2026-06-19T10:44:16.225Z",
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                "modifiedAttackVector": "NOT_DEFINED",
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                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
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                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
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                "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
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}



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