CVE-2026-21434

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{"affected": [{"affectedData": [{"product": "webtransport-go", "vendor": "quic-go", "versions": [{"status": "affected", "version": "< 0.10.0"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:quic-go:webtransport-go:*:*:*:*:*:go:*:*", "matchCriteriaId": "655FC296-1611-47D3-A71F-E5C093D2F463", "versionEndExcluding": "0.10.0", "versionStartIncluding": "0.3.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "webtransport-go is an implementation of the WebTransport protocol. From 0.3.0 to 0.9.0, an attacker can cause excessive memory consumption in webtransport-go's session implementation by sending a WT_CLOSE_SESSION capsule containing an excessively large Application Error Message. The implementation does not enforce the draft-mandated limit of 1024 bytes on this field, allowing a peer to send an arbitrarily large message payload that is fully read and stored in memory. This allows an attacker to consume an arbitrary amount of memory. The attacker must transmit the full payload to achieve the memory consumption, but the lack of any upper bound makes large-scale attacks feasible given sufficient bandwidth. This vulnerability is fixed in 0.10.0."}, {"lang": "es", "value": "webtransport-go es una implementaci\u00f3n del protocolo WebTransport. Desde 0.3.0 hasta 0.9.0, un atacante puede causar un consumo excesivo de memoria en la implementaci\u00f3n de sesi\u00f3n de webtransport-go al enviar una c\u00e1psula WT_CLOSE_SESSION que contiene un Mensaje de Error de Aplicaci\u00f3n excesivamente grande. La implementaci\u00f3n no aplica el l\u00edmite de 1024 bytes exigido por el borrador en este campo, lo que permite a un par enviar una carga \u00fatil de mensaje arbitrariamente grande que se lee y almacena completamente en memoria. Esto permite a un atacante consumir una cantidad arbitraria de memoria. El atacante debe transmitir la carga \u00fatil completa para lograr el consumo de memoria, pero la falta de cualquier l\u00edmite superior hace que los ataques a gran escala sean factibles dado un ancho de banda suficiente. Esta vulnerabilidad est\u00e1 corregida en 0.10.0."}], "id": "CVE-2026-21434", "lastModified": "2026-06-17T10:18:39.907", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "security-advisories@github.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-21434", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-02-12T18:45:50.348094Z", "version": "2.0.3"}}]}, "published": "2026-02-12T19:15:51.333", "references": [{"source": "security-advisories@github.com", "tags": ["Product", "Release Notes"], "url": "https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/quic-go/webtransport-go/security/advisories/GHSA-g6x7-jq8p-6q9q"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,0.10.0)"}}], "product": "webtransport-go", "vendor": "quic-go"}], "analysis": {"en": {"generated_at": "2026-04-18T18:08:35.271903+00:00", "value": {"mitigation_remediation": ["Upgrade the webtransport-go library to version 0.10.0 or later, which enforces the 1024\u2011byte limit on the error message field.", "If an immediate upgrade is not possible, implement network\u2011level controls such as rate limiting or traffic shaping to restrict the rate of incoming WT_CLOSE_SESSION capsules and limit the size of messages accepted.", "Continuously monitor memory usage of services running webtransport-go and set alerts for abnormal memory consumption so that any attempts to exhaust resources can be detected early."], "summary": {"action": "Patch", "impact": "Memory Exhaustion (DoS)"}, "threat_synthesis": {"affected_systems": "The flaw exists in quic-go's webtransport-go library versions 0.3.0 through 0.9.0. The issue was resolved in release 0.10.0. Administrators using any earlier version of the library should be aware that this vulnerability can be triggered by a malicious peer sending a specially crafted WT_CLOSE_SESSION capsule.", "description_and_impact": "webtransport-go, a WebTransport protocol implementation, lacked a mandated 1024\u2011byte limit for the Application Error Message field in the WT_CLOSE_SESSION capsule. This reflects a CWE\u2011770 weakness, illustrating resource exhaustion vulnerability. An attacker can send a capsule with an arbitrarily large error message that the implementation reads and stores entirely in memory, allowing the attacker to consume an arbitrary amount of memory on the target. The vulnerability can be leveraged to cause a denial\u2011of\u2011service by exhausting memory resources, with the severity classified as moderate (CVSS 5.3).", "risk_and_exploitability": "The CVSS score of 5.3 indicates moderate risk, and the EPSS is listed as less than 1\u202f%, implying a very low likelihood of widespread exploitation. The vulnerability is not currently listed in the CISA KEV catalog. An attacker must send the full payload to trigger the memory allocation, but the lack of an upper bound makes large\u2011scale attacks feasible if sufficient bandwidth is available. The likely attack vector is inferred from the description as a remote peer connecting over the WebTransport protocol to the vulnerable service."}}}}, "created": "2026-02-13T21:35:25.506862+00:00", "updated": "2026-04-18T18:15:06.601829+00:00", "vendors": ["quic-go", "quic-go$PRODUCT$webtransport-go"]}