The application must pass untrusted input into a disposition parameter of Tesla.Multipart.add_field/4, Tesla.Multipart.add_file/3, or Tesla.Multipart.add_file_content/4.
Improper Encoding or Escaping of Output vulnerability in elixir-tesla tesla allows multipart part header injection via unescaped Content-Disposition parameter values.
Tesla.Multipart.part_headers_for_disposition/1 interpolates each disposition parameter as #{k}=\"#{v}\" with no validation of CR (\\r), LF (\\n), or double-quote characters. The values come verbatim from the caller via Tesla.Multipart.add_field/4 (the name parameter), Tesla.Multipart.add_file/3, and Tesla.Multipart.add_file_content/4 (both the filename parameter and other disposition opts). A \" in the value closes the quoted parameter early; a \\r\\n ends the Content-Disposition header line and starts a new part header (such as a forged Content-Type), or, after a second \\r\\n, ends the entire part header block and prepends bytes to the part body. The default-filename path in add_file/3 derives the filename via Path.basename/1, which does not strip CR or LF, so any application forwarding a partially-attacker-controlled file path inherits the same issue.
This issue affects tesla: from 0.8.0 before 1.18.3.
" }, { "base64": false, "type": "text/markdown", "value": "Improper Encoding or Escaping of Output vulnerability in elixir-tesla tesla allows multipart part header injection via unescaped `Content-Disposition` parameter values.\n\n`Tesla.Multipart.part_headers_for_disposition/1` interpolates each disposition parameter as `#{k}=\"#{v}\"` with no validation of CR (`\\r`), LF (`\\n`), or double-quote characters. The values come verbatim from the caller via `Tesla.Multipart.add_field/4` (the `name` parameter), `Tesla.Multipart.add_file/3`, and `Tesla.Multipart.add_file_content/4` (both the `filename` parameter and other disposition opts). A `\"` in the value closes the quoted parameter early; a `\\r\\n` ends the `Content-Disposition` header line and starts a new part header (such as a forged `Content-Type`), or, after a second `\\r\\n`, ends the entire part header block and prepends bytes to the part body. The default-filename path in `add_file/3` derives the filename via `Path.basename/1`, which does not strip CR or LF, so any application forwarding a partially-attacker-controlled file path inherits the same issue.\n\nThis issue affects tesla: from 0.8.0 before 1.18.3." } ], "value": "Improper Encoding or Escaping of Output vulnerability in elixir-tesla tesla allows multipart part header injection via unescaped Content-Disposition parameter values.\n\nTesla.Multipart.part_headers_for_disposition/1 interpolates each disposition parameter as #{k}=\"#{v}\" with no validation of CR (\\r), LF (\\n), or double-quote characters. The values come verbatim from the caller via Tesla.Multipart.add_field/4 (the name parameter), Tesla.Multipart.add_file/3, and Tesla.Multipart.add_file_content/4 (both the filename parameter and other disposition opts). A \" in the value closes the quoted parameter early; a \\r\\n ends the Content-Disposition header line and starts a new part header (such as a forged Content-Type), or, after a second \\r\\n, ends the entire part header block and prepends bytes to the part body. The default-filename path in add_file/3 derives the filename via Path.basename/1, which does not strip CR or LF, so any application forwarding a partially-attacker-controlled file path inherits the same issue.\n\nThis issue affects tesla: from 0.8.0 before 1.18.3." } ], "impacts": [ { "capecId": "CAPEC-105", "descriptions": [ { "lang": "en", "value": "CAPEC-105 HTTP Request Splitting" } ] } ], "metrics": [ { "cvssV4_0": { "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "LOCAL", "baseScore": 2.1, "baseSeverity": "LOW", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED" }, "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ] } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-116", "description": "CWE-116 Improper Encoding or Escaping of Output", "lang": "en", "type": "CWE" } ] } ], "providerMetadata": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-24T21:00:20.385Z" }, "references": [ { "tags": [ "vendor-advisory", "related" ], "url": "https://github.com/elixir-tesla/tesla/security/advisories/GHSA-28jh-g32x-v9v4" }, { "name": "EEF CNA record for CVE-2026-48598", "tags": [ "related" ], "url": "https://cna.erlef.org/cves/CVE-2026-48598.html" }, { "name": "OSV record EEF-CVE-2026-48598", "tags": [ "related" ], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-48598" }, { "name": "Introducing commit 6ebfdb9 in elixir-tesla/tesla", "tags": [ "related" ], "url": "https://github.com/elixir-tesla/tesla/commit/6ebfdb9abe9c6f119408045b933d82462decd351" }, { "name": "Fix commit bb1a2c3 in elixir-tesla/tesla", "tags": [ "patch" ], "url": "https://github.com/elixir-tesla/tesla/commit/bb1a2c3da2775924d96e3db8e315dcc4d5d2246e" } ], "source": { "discovery": "EXTERNAL" }, "title": "CRLF injection in Tesla.Multipart disposition parameters allows multipart part header injection", "workarounds": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "Validate disposition parameter values before passing them to Tesla.Multipart.add_field/4, Tesla.Multipart.add_file/3, or Tesla.Multipart.add_file_content/4, rejecting any value that contains \\r, \\n, or \".