CVE-2026-48598: Tesla Tesla Vulnerable To Multipart Part Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-28jh-g32x-v9v4",
  "modified" : "2026-07-10T00:04:37Z",
  "published" : "2026-07-10T00:04:37Z",
  "aliases" : [ "CVE-2026-48598" ],
  "summary" : "Tesla vulnerable to multipart part smuggling via unescaped `content-disposition` values",
  "details" : "### Summary\n\n`Tesla.Multipart.part_headers_for_disposition/1` interpolates `Content-Disposition` parameter values (field name, filename, and other opts) verbatim into the part header line without encoding or escaping any special characters. An attacker who controls a filename, field name, or other disposition parameter can use unescaped double-quotes to inject extra disposition key-value pairs, or CRLF sequences to inject additional part headers or prepend bytes to the part body.\n\n### Details\n\n`part_headers_for_disposition/1` in `lib/tesla/multipart.ex` formats each disposition parameter as `k=\"v\"` with no sanitization. Values flow in from `add_field/4` (the `name` argument), `add_file/3` and `add_file_content/4` (the `filename` argument and any disposition opts). A `\"` in the value closes the quoted parameter early, allowing extra `; key=\"value\"` pairs to be appended. A `\\r\\n` ends the `Content-Disposition` header line entirely, with subsequent bytes interpreted as additional part headers (e.g. a forged `Content-Type`); a second `\\r\\n` ends the whole part header block and prepends attacker bytes to the part body.\n\nThe default-filename path in `add_file/3` derives the name via `Path.basename/1`, which does not strip CR or LF, so any code that forwards a partially attacker-controlled file path is equally vulnerable.\n\n### PoC\n\n1. Call `Tesla.Multipart.add_file_content/4` with a filename containing `\\r\\nX-Injected: evil`.\n2. POST the multipart body to any upstream via any Tesla adapter.\n3. The upstream receives `X-Injected: evil` as a standalone header line on the affected part.\n\n### Impact\n\nLow severity (CVSS v4.0: 2.1). Any application using `tesla` 0.8.0 through 1.18.2 that passes untrusted input into `add_field/4`, `add_file/3`, or `add_file_content/4` disposition parameters is affected. Consequences range from forging part-level headers to body prepending against lenient multipart parsers. Fixed in tesla 1.18.3.\n\n### Workarounds\n\nValidate disposition parameter values before passing them to the multipart API, rejecting any value that contains `\\r`, `\\n`, or `\"`.\n\n### Resources\n\n* Introduction commit: https://github.com/elixir-tesla/tesla/commit/6ebfdb9abe9c6f119408045b933d82462decd351\n* Patch commit: https://github.com/elixir-tesla/tesla/commit/bb1a2c3da2775924d96e3db8e315dcc4d5d2246e",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "tesla"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.8.0"
      }, {
        "fixed" : "1.18.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/elixir-tesla/tesla/security/advisories/GHSA-28jh-g32x-v9v4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-48598"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/elixir-tesla/tesla/commit/bb1a2c3da2775924d96e3db8e315dcc4d5d2246e"
  }, {
    "type" : "WEB",
    "url" : "https://cna.erlef.org/cves/CVE-2026-48598.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/elixir-tesla/tesla"
  }, {
    "type" : "WEB",
    "url" : "https://osv.dev/vulnerability/EEF-CVE-2026-48598"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-116" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-10T00:04:37Z",
    "nvd_published_at" : "2026-06-02T20:16:38Z"
  }
}