{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-3849", "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "state": "PUBLISHED", "assignerShortName": "wolfSSL", "dateReserved": "2026-03-09T19:50:50.081Z", "datePublished": "2026-03-19T20:29:30.839Z", "dateUpdated": "2026-03-19T20:29:30.839Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "shortName": "wolfSSL", "dateUpdated": "2026-03-19T20:29:30.839Z"}, "title": "Buffer Overflow in HPKE via Oversized ECH Config", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-787", "description": "CWE-787: Out-of-bounds Write", "type": "CWE"}]}], "affected": [{"vendor": "wolfSSL Inc.", "product": "wolfSSL", "versions": [{"status": "affected", "version": "v5.6.0-stable", "lessThanOrEqual": "v5.8.4-stable", "versionType": "git"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<div>Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech.</div><div><br></div>"}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl/pull/9737"}], "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": "LOW", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "DIFFUSE", "vulnerabilityResponseEffort": "MODERATE", "providerUrgency": "AMBER", "version": "4.0", "baseSeverity": "MEDIUM", "baseScore": 6.9, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/V:D/RE:M/U:Amber"}}], "credits": [{"lang": "en", "value": "Haruto Kimura (Stella)", "type": "finder"}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech."}], "id": "CVE-2026-3849", "lastModified": "2026-03-19T21:17:13.407", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.9, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "AMBER", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "DIFFUSE", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/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:D/RE:M/U:Amber", "version": "4.0", "vulnAvailabilityImpact": "LOW", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "MODERATE"}, "source": "facts@wolfssl.com", "type": "Secondary"}]}, "published": "2026-03-19T21:17:13.407", "references": [{"source": "facts@wolfssl.com", "url": "https://github.com/wolfSSL/wolfssl/pull/9737"}], "sourceIdentifier": "facts@wolfssl.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "facts@wolfssl.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[v5.6.0-stable,v5.8.4-stable]"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "wolfSSL", "source": "cna", "vendor": "wolfSSL Inc."}, "product": "wolfssl", "vendor": "wolfssl"}], "analysis": {"en": {"generated_at": "2026-03-19T21:21:22.144681+00:00", "value": {"mitigation_remediation": ["Upgrade wolfSSL to a patched version that addresses CVE\u20112026\u20113849", "If upgrading is not immediately possible, disable ECH by ensuring enable\u2011ech is not set or is disabled in configuration", "Verify that ECH support has been removed or patched via vendor documentation", "Monitor network traffic for suspicious ECH configurations if temporary loss of functionality is acceptable"], "summary": {"action": "Patch Now", "impact": "Stack Buffer Overflow with potential remote execution."}, "threat_synthesis": {"affected_systems": "Affected vendors and products include wolfSSL Inc.\u2019s wolfSSL library, specifically version 5.8.4 where ECH support is compiled in. Clients using this version with ECH enabled (through the enable\u2011ech configuration) are susceptible. The vulnerability is client\u2011side only; it is triggered during the processing of an ECH configuration received from a TLS server.", "description_and_impact": "The vulnerability is a stack buffer overflow in the wc_HpkeLabeledExtract function within wolfSSL 5.8.4\u2019s ECH support. A maliciously crafted ECH configuration can overflow the buffer, potentially leading to remote code execution or a client crash. This weakness is identified as CWE\u2011787.", "risk_and_exploitability": "The CVSS score is 6.9 indicating moderate severity, with no EPSS data available and not listed in the KEV catalog. Exploitation would require a TLS server that sends a crafted ECH configuration to a client running the vulnerable library. The attack vector is remote, network\u2011based, and relies on the client accepting ECH. If successful, an attacker could execute arbitrary code or cause a denial of service."}}}}, "created": "2026-03-20T08:56:15.517307+00:00", "updated": "2026-03-20T11:06:25.198589+00:00", "vendors": ["wolfssl", "wolfssl$PRODUCT$wolfssl"]}