Vulnerability-Lookup

CVE-2026-23527 (GCVE-0-2026-23527)

Vulnerability from cvelistv5 – Published: 2026-01-15 19:24 – Updated: 2026-01-15 20:00

Title

Request Smuggling (TE.TE) in h3 v1

Summary

H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for "chunked", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5.

Severity ?

8.9 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L

CWE

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Assigner

GitHub_M

References

URL

Tags

	https://github.com/h3js/h3/security/advisories/GH…	x_refsource_CONFIRM
	https://github.com/h3js/h3/commit/618ccf4f37b8b61…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	h3js	h3	Affected: < 1.15.5

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-23527",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-01-15T19:59:57.020909Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-01-15T20:00:06.302Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "h3",
          "vendor": "h3js",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.15.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for \"chunked\", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 8.9,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-15T19:24:20.514Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg"
        },
        {
          "name": "https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097"
        }
      ],
      "source": {
        "advisory": "GHSA-mp2g-9vg9-f4cg",
        "discovery": "UNKNOWN"
      },
      "title": "Request Smuggling (TE.TE) in h3 v1"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-23527",
    "datePublished": "2026-01-15T19:24:20.514Z",
    "dateReserved": "2026-01-13T18:22:43.981Z",
    "dateUpdated": "2026-01-15T20:00:06.302Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23527\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-01-15T20:16:05.620\",\"lastModified\":\"2026-01-23T18:50:35.587\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for \\\"chunked\\\", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L\",\"baseScore\":8.9,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":2.2,\"impactScore\":6.0},{\"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\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-444\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:h3:h3:*:*:*:*:*:node.js:*:*\",\"versionEndExcluding\":\"1.15.5\",\"matchCriteriaId\":\"8AEE0C29-3BA5-4765-82CB-0CE73ACCEB77\"}]}]}],\"references\":[{\"url\":\"https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Patch\"]},{\"url\":\"https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Exploit\",\"Vendor Advisory\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-23527\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-01-15T19:59:57.020909Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-01-15T19:59:59.151Z\"}}], \"cna\": {\"title\": \"Request Smuggling (TE.TE) in h3 v1\", \"source\": {\"advisory\": \"GHSA-mp2g-9vg9-f4cg\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"CHANGED\", \"version\": \"3.1\", \"baseScore\": 8.9, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"LOW\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}], \"affected\": [{\"vendor\": \"h3js\", \"product\": \"h3\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 1.15.5\"}]}], \"references\": [{\"url\": \"https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg\", \"name\": \"https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097\", \"name\": \"https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for \\\"chunked\\\", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-444\", \"description\": \"CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-01-15T19:24:20.514Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-23527\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-15T20:00:06.302Z\", \"dateReserved\": \"2026-01-13T18:22:43.981Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-01-15T19:24:20.514Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

GHSA-MP2G-9VG9-F4CG

Vulnerability from github – Published: 2026-01-15 20:10 – Updated: 2026-01-15 22:34

Summary

h3 v1 has Request Smuggling (TE.TE) issue

Details

I was digging into h3 v1 (specifically v1.15.4) and found a critical HTTP Request Smuggling vulnerability.

Basically, readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for "chunked", but per the RFC, this header should be case-insensitive.

The Bug: If I send a request with Transfer-Encoding: ChuNked (mixed case), h3 misses it. Since it doesn't see "chunked" and there's no Content-Length, it assumes the body is empty and processes the request immediately.

This leaves the actual body sitting on the socket, which triggers a classic TE.TE Desync (Request Smuggling) if the app is running behind a Layer 4 proxy or anything that doesn't normalize headers (like AWS NLB or Node proxies).

Vulnerable Code (src/utils/body.ts):

if (
    !Number.parseInt(event.node.req.headers["content-length"] || "") &&
    !String(event.node.req.headers["transfer-encoding"] ?? "")
      .split(",")
      .map((e) => e.trim())
      .filter(Boolean)
      .includes("chunked") // <--- This is the issue. "ChuNkEd" returns false here.
  ) {
    return Promise.resolve(undefined);
  }

I verified this locally:

Sent a Transfer-Encoding: ChunKed request without a closing 0 chunk.
Express hangs (correctly waiting for data).
h3 responds immediately (vulnerable, thinks body is length 0).

Impact: Since H3/Nuxt/Nitro is often used in containerized setups behind TCP load balancers, an attacker can use this to smuggle requests past WAFs or desynchronize the socket to poison other users' connections.

Fix: Just need to normalize the header value before checking: .map((e) => e.trim().toLowerCase())

Severity ?

8.9 (High)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.15.4"
      },
      "package": {
        "ecosystem": "npm",
        "name": "h3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.15.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-23527"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-444"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-15T20:10:51Z",
    "nvd_published_at": "2026-01-15T20:16:05Z",
    "severity": "HIGH"
  },
  "details": "I was digging into h3 v1 (specifically v1.15.4) and found a critical HTTP Request Smuggling vulnerability.\n\nBasically, `readRawBody` is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for \"chunked\", but per the RFC, this header should be case-insensitive.\n\n**The Bug**: If I send a request with Transfer-Encoding: ChuNked (mixed case), h3 misses it. Since it doesn\u0027t see \"chunked\" and there\u0027s no Content-Length, it assumes the body is empty and processes the request immediately.\n\nThis leaves the actual body sitting on the socket, which triggers a classic TE.TE Desync (Request Smuggling) if the app is running behind a Layer 4 proxy or anything that doesn\u0027t normalize headers (like AWS NLB or Node proxies).\n\n**Vulnerable Code** (`src/utils/body.ts`):\n\n```js\nif (\n    !Number.parseInt(event.node.req.headers[\"content-length\"] || \"\") \u0026\u0026\n    !String(event.node.req.headers[\"transfer-encoding\"] ?? \"\")\n      .split(\",\")\n      .map((e) =\u003e e.trim())\n      .filter(Boolean)\n      .includes(\"chunked\") // \u003c--- This is the issue. \"ChuNkEd\" returns false here.\n  ) {\n    return Promise.resolve(undefined);\n  }\n```\n\nI verified this locally:\n\n- Sent a `Transfer-Encoding: ChunKed` request without a closing 0 chunk.\n- Express hangs (correctly waiting for data).\n- h3 responds immediately (vulnerable, thinks body is length 0).\n\n**Impact**: Since H3/Nuxt/Nitro is often used in containerized setups behind TCP load balancers, an attacker can use this to smuggle requests past WAFs or desynchronize the socket to poison other users\u0027 connections.\n\n**Fix**: Just need to normalize the header value before checking: ` .map((e) =\u003e e.trim().toLowerCase())`",
  "id": "GHSA-mp2g-9vg9-f4cg",
  "modified": "2026-01-15T22:34:08Z",
  "published": "2026-01-15T20:10:51Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23527"
    },
    {
      "type": "WEB",
      "url": "https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/h3js/h3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/h3js/h3/releases/tag/v1.15.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "h3 v1 has Request Smuggling (TE.TE) issue"
}

FKIE_CVE-2026-23527

Vulnerability from fkie_nvd - Published: 2026-01-15 20:16 - Updated: 2026-01-23 18:50

Severity ?

8.9 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097	Patch
	security-advisories@github.com	https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	h3	h3	*

JSON

To clipboard

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:h3:h3:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "8AEE0C29-3BA5-4765-82CB-0CE73ACCEB77",
              "versionEndExcluding": "1.15.5",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for \"chunked\", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5."
    }
  ],
  "id": "CVE-2026-23527",
  "lastModified": "2026-01-23T18:50:35.587",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 8.9,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 6.0,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-01-15T20:16:05.620",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

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.

Action not permitted

CVE-2026-23527 (GCVE-0-2026-23527)

GHSA-MP2G-9VG9-F4CG

FKIE_CVE-2026-23527

Tags

Sightings

Nomenclature