CVE-2026-3849 (GCVE-0-2026-3849)

Vulnerability from cvelistv5 – Published: 2026-03-19 20:29 – Updated: 2026-03-25 14:21
VLAI?
Title
Buffer Overflow in HPKE via Oversized ECH Config
Summary
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.
Severity ?
6.9 (Medium)
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
CWE
Assigner
References
Impacted products
Vendor Product Version
wolfSSL Inc. wolfSSL Affected: v5.6.0-stable , ≤ v5.8.4-stable (git)
Create a notification for this product.
Credits
Haruto Kimura (Stella)
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-3849",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T14:21:05.452094Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-25T14:21:17.389Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "wolfSSL",
          "vendor": "wolfSSL Inc.",
          "versions": [
            {
              "lessThanOrEqual": "v5.8.4-stable",
              "status": "affected",
              "version": "v5.6.0-stable",
              "versionType": "git"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Haruto Kimura (Stella)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cdiv\u003eStack 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.\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e"
            }
          ],
          "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "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/V:D/RE:M/U:Amber",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "MODERATE"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-787",
              "description": "CWE-787: Out-of-bounds Write",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-19T20:29:30.839Z",
        "orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
        "shortName": "wolfSSL"
      },
      "references": [
        {
          "url": "https://github.com/wolfSSL/wolfssl/pull/9737"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Buffer Overflow in HPKE via Oversized ECH Config",
      "x_generator": {
        "engine": "Vulnogram 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
    "assignerShortName": "wolfSSL",
    "cveId": "CVE-2026-3849",
    "datePublished": "2026-03-19T20:29:30.839Z",
    "dateReserved": "2026-03-09T19:50:50.081Z",
    "dateUpdated": "2026-03-25T14:21:17.389Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-3849\",\"sourceIdentifier\":\"facts@wolfssl.com\",\"published\":\"2026-03-19T21:17:13.407\",\"lastModified\":\"2026-03-26T18:20:36.580\",\"vulnStatus\":\"Analyzed\",\"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.\"},{\"lang\":\"es\",\"value\":\"Desbordamiento de b\u00fafer de pila en wc_HpkeLabeledExtract a trav\u00e9s de una configuraci\u00f3n ECH sobredimensionada. Exist\u00eda una vulnerabilidad en el soporte ECH (Encrypted Client Hello) de wolfSSL 5.8.4, donde una configuraci\u00f3n ECH creada maliciosamente podr\u00eda causar un desbordamiento de b\u00fafer de pila en el lado del cliente, lo que podr\u00eda llevar a una ejecuci\u00f3n remota potencial y a un fallo del programa del cliente. Esto podr\u00eda ser explotado por un servidor TLS malicioso que soporte ECH. Tenga en cuenta que ECH est\u00e1 desactivado por defecto y solo se habilita con enable-ech.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"facts@wolfssl.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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\",\"baseScore\":6.9,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"LOW\",\"vulnAvailabilityImpact\":\"LOW\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"DIFFUSE\",\"vulnerabilityResponseEffort\":\"MODERATE\",\"providerUrgency\":\"AMBER\"}}],\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"facts@wolfssl.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-787\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.6.0\",\"versionEndExcluding\":\"5.9.0\",\"matchCriteriaId\":\"2D7DB269-3D15-4DD9-B47E-2A94CC36BE3E\"}]}]}],\"references\":[{\"url\":\"https://github.com/wolfSSL/wolfssl/pull/9737\",\"source\":\"facts@wolfssl.com\",\"tags\":[\"Issue Tracking\",\"Patch\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-3849\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-25T14:21:05.452094Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-25T14:21:10.835Z\"}}], \"cna\": {\"title\": \"Buffer Overflow in HPKE via Oversized ECH Config\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Haruto Kimura (Stella)\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6.9, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"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/V:D/RE:M/U:Amber\", \"exploitMaturity\": \"NOT_DEFINED\", \"providerUrgency\": \"AMBER\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"LOW\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"LOW\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"MODERATE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"vendor\": \"wolfSSL Inc.\", \"product\": \"wolfSSL\", \"versions\": [{\"status\": \"affected\", \"version\": \"v5.6.0-stable\", \"versionType\": \"git\", \"lessThanOrEqual\": \"v5.8.4-stable\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/wolfSSL/wolfssl/pull/9737\"}], \"x_generator\": {\"engine\": \"Vulnogram 1.0.0\"}, \"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\", \"value\": \"\u003cdiv\u003eStack 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.\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-787\", \"description\": \"CWE-787: Out-of-bounds Write\"}]}], \"providerMetadata\": {\"orgId\": \"50d2cd11-d01a-48ed-9441-5bfce9d63b27\", \"shortName\": \"wolfSSL\", \"dateUpdated\": \"2026-03-19T20:29:30.839Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-3849\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-25T14:21:17.389Z\", \"dateReserved\": \"2026-03-09T19:50:50.081Z\", \"assignerOrgId\": \"50d2cd11-d01a-48ed-9441-5bfce9d63b27\", \"datePublished\": \"2026-03-19T20:29:30.839Z\", \"assignerShortName\": \"wolfSSL\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.