Unvalidated chunk-size line tail in Mint HTTP/1 client enables response smuggling against strict intermediaries on pooled connections

{
  "id": "19270aa99c6269b2a19f60396e741607b0b28c7b5ef5c1d472d49004ee99bc76",
  "url": "https://osv.dev/vulnerability/CVE-2026-82672",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Unvalidated chunk-size line tail in Mint HTTP/1 client enables response smuggling against strict intermediaries on pooled connections",
    "summary": "Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize a strict intermediary and the Mint client on a pooled connection, enabling response-queue poisoning against subsequent requests that share the connection. Mint.HTTP1.Parse.chunk_size/1 in lib/mint/http1/parse.ex stops at the first non-hexadecimal byte of a chunked response's chunk-size line and returns the remainder unexamined. Mint.HTTP1.decode_body/5 in lib/mint/http1.ex then discards every byte up to the CRLF with Parse.ignore_until_crlf/1, so the accepted grammar is a run of hex digits followed by arbitrary bytes, where RFC 9112 permits only a ;-introduced chunk extension. Lines such as 5ZZZZZ and 5 9 are accepted as chunk size 5, and 0ZZZZ is accepted as the terminating chunk that ends the message body. An RFC-strict intermediary rejects such a line while Mint accepts it, so the two disagree on chunk boundaries and on where the response ends. This issue affects mint: from 0.1.0 before 1.10.1.",
    "evidence": "osv:CVE-2026-82672",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-82672",
      "aliases": [
        "CVE-2026-82672",
        "EEF-CVE-2026-82672",
        "GHSA-rj5m-69wp-cxq9"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/elixir-mint/mint",
              "type": "GIT",
              "events": [
                {
                  "introduced": "60089586ec7adc9fddb09f69a2f5919ba9ac7f33"
                },
                {
                  "fixed": "c82377838dc6e275ef40bafa664fbcdf50270c60"
                },
                {
                  "introduced": "47889857fb36f07606ad9c2e52080d202d419058"
                },
                {
                  "fixed": "9e9ae10cb6321879b8cf74dea3dd3e91d0e72f41"
                },
                {
                  "fixed": "60089586ec7adc9fddb09f69a2f5919ba9ac7f33"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "60089586ec7adc9fddb09f69a2f5919ba9ac7f33"
                      },
                      {
                        "fixed": "c82377838dc6e275ef40bafa664fbcdf50270c60"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0.1.0"
                      },
                      {
                        "fixed": "1.10.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "60089586ec7adc9fddb09f69a2f5919ba9ac7f33"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c82377838dc6e275ef40bafa664fbcdf50270c60"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.10.0",
            "v1.9.3",
            "v1.9.2",
            "v1.9.1",
            "v1.9.0",
            "v1.8.0",
            "v1.7.1",
            "v1.7.0",
            "v1.6.2",
            "v1.6.1",
            "v1.6.0",
            "v1.5.2",
            "v1.5.1",
            "v1.5.0",
            "v1.4.2",
            "v1.4.1",
            "v1.4.0",
            "v1.3.0",
            "v1.2.1",
            "v1.2.0",
            "v1.1.0",
            "v1.0.0",
            "v0.5.0",
            "v0.4.0",
            "v0.2.1",
            "v0.2.0",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82672.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.148865116Z",
      "provider": "osv",
      "references": [
        "https://cna.erlef.org/cves/CVE-2026-82672.html",
        "https://github.com",
        "https://osv.dev/vulnerability/EEF-CVE-2026-82672",
        "https://repo.hex.pm",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82672.json",
        "https://github.com/elixir-mint/mint/security/advisories/GHSA-rj5m-69wp-cxq9",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-82672",
        "https://github.com/elixir-mint/mint/commit/60089586ec7adc9fddb09f69a2f5919ba9ac7f33",
        "https://github.com/elixir-mint/mint/commit/c82377838dc6e275ef40bafa664fbcdf50270c60",
        "https://github.com/elixir-mint/mint"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-444"
        ],
        "cna_assigner": "EEF",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82672.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-82672",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 510015,
  "published_at": "2026-09-19T17:00:31.648+00:00"
}