eef-cve-2026-82672

{
  "affected": [
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-82672.json"
      },
      "package": {
        "ecosystem": "Hex",
        "name": "mint",
        "purl": "pkg:hex/mint"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.1.0"
            },
            {
              "fixed": "1.10.1"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": [
        "0.1.0",
        "0.2.0",
        "0.2.1",
        "0.3.0",
        "0.4.0",
        "0.5.0",
        "1.0.0",
        "1.1.0",
        "1.10.0",
        "1.2.0",
        "1.2.1",
        "1.3.0",
        "1.4.0",
        "1.4.1",
        "1.4.2",
        "1.5.0",
        "1.5.1",
        "1.5.2",
        "1.6.0",
        "1.6.1",
        "1.6.2",
        "1.7.0",
        "1.7.1",
        "1.8.0",
        "1.9.0",
        "1.9.1",
        "1.9.2",
        "1.9.3"
      ]
    },
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-82672.json"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "60089586ec7adc9fddb09f69a2f5919ba9ac7f33"
            },
            {
              "fixed": "c82377838dc6e275ef40bafa664fbcdf50270c60"
            }
          ],
          "repo": "https://github.com/elixir-mint/mint",
          "type": "GIT"
        }
      ],
      "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"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-82672",
    "GHSA-rj5m-69wp-cxq9"
  ],
  "credits": [
    {
      "name": "Eurico Nicacio",
      "type": "FINDER"
    },
    {
      "name": "Eurico Nicacio",
      "type": "REPORTER"
    },
    {
      "name": "Eric Meadows-Jönsson",
      "type": "REMEDIATION_DEVELOPER"
    },
    {
      "name": "Andrea Leopardi",
      "type": "REMEDIATION_REVIEWER"
    }
  ],
  "database_specific": {
    "capec_ids": [
      "CAPEC-273"
    ],
    "cpe_ids": [
      "cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"
    ],
    "cwe_ids": [
      "CWE-444"
    ]
  },
  "details": "## Summary\n\nInconsistent 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.\n\n`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.\n\nThis issue affects mint: from 0.1.0 before 1.10.1.\n\n## Details\n\n**1. Chunk-size parsing.** `Mint.HTTP1.Parse.chunk_size/1` in `lib/mint/http1/parse.ex` folds leading hexadecimal digits into an accumulator through `parse_hex_prefix/3` and, on the first byte that is not a hex digit, returns `{:ok, size, rest}` with `rest` unexamined. The sign and digit-count checks added by earlier fixes constrain only the digits.\n\n**2. Tail skipping.** The caller, `Mint.HTTP1.decode_body/5` in `lib/mint/http1.ex`, hands `rest` to `Parse.ignore_until_crlf/1`, which advances over any byte until it finds CRLF. Nothing between the last hex digit and the CRLF is validated, so the accepted grammar is `1*HEXDIG *OCTET CRLF`, where RFC 9112 section 7.1 allows only an optional `;`-introduced `chunk-ext`. The same tolerance applies to the terminating zero-length chunk, which is the token that ends the message body.\n\n**3. Parser disagreement.** The sibling `Content-Length` parser, `Mint.HTTP1.Parse.content_length_header/1`, trims trailing whitespace and requires the whole remaining value to be digits, rejecting anything else. An RFC-strict intermediary that rejects or reframes a chunk-size line with a non-extension tail, on a connection where Mint accepts it, yields a framing disagreement about chunk length and, through the terminating chunk, about where the message ends.\n\n## Proof of concept\n\n1. Start a loopback TCP server that serves one `HTTP/1.1 200 OK` response with `transfer-encoding: chunked` and controls the chunk-size line byte for byte.\n2. Connect with `Mint.HTTP1` (mint 1.10.0 from Hex), send a request and stream the response.\n3. Positive controls: chunk-size lines `+5`, `Z5` and `00000000000000005` are refused with `:invalid_chunk_size`, confirming the build carries the earlier chunk-size fixes.\n4. Baseline: `5` and `5;name=value` are accepted with body `hello`.\n5. Finding: `5ZZZZZ`, `5 anything at all`, `5<TAB>foo`, `5 9` and `5}~!` are each accepted as chunk size 5 with body `hello`.\n6. Terminator: `0ZZZZ` and `0 9` in place of the final `0` chunk are accepted and end the body.\n7. Contrast: `Content-Length: +5`, `Content-Length: 5ZZZ` and `Content-Length: 5 9` are refused with `:invalid_content_length_header` in the same run.\n\nThe reporter ran this on Elixir 1.18 / OTP 27 and Elixir 1.18.4 / OTP 28 with identical results.\n\n## Impact\n\nA malicious or attacker-influenced HTTP/1 origin behind an RFC-strict intermediary can make the intermediary and the Mint client disagree on chunk boundaries and on where the response body ends. On a pooled keep-alive connection that disagreement lets bytes from one response be attributed to the next, poisoning the responses returned to unrelated requests that share the connection.\n\n## Configurations\n\nExploitation requires a deployment topology in which an RFC-strict HTTP/1 intermediary (proxy, load balancer, or WAF) sits between the Mint client and the attacker-influenced origin, and HTTP/1 connections between the client and the intermediary are reused across requests (keep-alive with connection pooling). Mint clients that talk directly to an origin without an intermediary, or that do not reuse connections, are not exploitable for response-queue poisoning even if the vulnerable parsing behavior is present.",
  "id": "EEF-CVE-2026-82672",
  "modified": "2026-09-19T17:25:50.946668258Z",
  "published": "2026-09-19T17:00:31.648Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/elixir-mint/mint/security/advisories/GHSA-rj5m-69wp-cxq9"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-82672.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/elixir-mint/mint/commit/60089586ec7adc9fddb09f69a2f5919ba9ac7f33"
    },
    {
      "type": "FIX",
      "url": "https://github.com/elixir-mint/mint/commit/c82377838dc6e275ef40bafa664fbcdf50270c60"
    },
    {
      "type": "PACKAGE",
      "url": "https://hex.pm/packages/mint"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Unvalidated chunk-size line tail in Mint HTTP/1 client enables response smuggling against strict intermediaries on pooled connections"
}