{"id":"GHSA-q7jx-v53g-848w","summary":"Tesla has CRLF injection in request `Content-Type` header via `add_content_type_param`","details":"### Summary\n\n`Tesla.Multipart.add_content_type_param/2` appends caller-supplied strings to the multipart `Content-Type` header with no validation. A param value containing `\\r\\n` splits the header line, allowing an attacker who controls any content-type parameter (charset, boundary parameter, etc.) to inject arbitrary headers into the outbound HTTP request.\n\n### Details\n\n`add_content_type_param/2` in `lib/tesla/multipart.ex` stores the supplied string directly in `multipart.content_type_params` without any CR/LF check. `headers/1` then joins all params with `\"; \"` and appends the result verbatim to the `Content-Type` header value. Because HTTP headers are delimited by `\\r\\n`, a param containing that sequence breaks out of the header field and introduces new header lines before the adapter writes the request to the socket.\n\nThe precondition is that untrusted input reaches `add_content_type_param/2`, which is the normal pattern for applications that accept user-supplied charset values, file type parameters, or any other content-type extension fields.\n\n### PoC\n\n1. Call `Tesla.Multipart.add_content_type_param/2` with a value containing `\\r\\nX-Injected: pwned`.\n2. Pass the resulting `Multipart` struct as the request body via any Tesla adapter.\n3. The raw request on the wire contains `X-Injected: pwned` as a standalone header line.\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 `Tesla.Multipart.add_content_type_param/2` is affected. Consequences range from forging arbitrary outbound request headers to potential request smuggling against the upstream server. Fixed in tesla 1.18.3.\n\n### Workarounds\n\nValidate content-type parameter strings before passing them to `Tesla.Multipart.add_content_type_param/2`, rejecting any value that contains `\\r` or `\\n`.\n\n### Reesources\n\n* Introduction commit: https://github.com/elixir-tesla/tesla/commit/6ebfdb9abe9c6f119408045b933d82462decd351\n* Patch commit: https://github.com/elixir-tesla/tesla/commit/23601edac5d22ba9407b427967b5bdbda201aec2","aliases":["CVE-2026-48596","EEF-CVE-2026-48596"],"modified":"2026-07-10T00:15:09.320783192Z","published":"2026-07-10T00:03:12Z","database_specific":{"cwe_ids":["CWE-113","CWE-93"],"severity":"LOW","github_reviewed":true,"github_reviewed_at":"2026-07-10T00:03:12Z","nvd_published_at":"2026-06-02T20:16:38Z"},"references":[{"type":"WEB","url":"https://github.com/elixir-tesla/tesla/security/advisories/GHSA-q7jx-v53g-848w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48596"},{"type":"WEB","url":"https://github.com/elixir-tesla/tesla/commit/23601edac5d22ba9407b427967b5bdbda201aec2"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-48596.html"},{"type":"PACKAGE","url":"https://github.com/elixir-tesla/tesla"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-48596"}],"affected":[{"package":{"name":"tesla","ecosystem":"Hex","purl":"pkg:hex/tesla"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.8.0"},{"fixed":"1.18.3"}]}],"versions":["0.10.0","0.8.0","0.9.0","1.0.0","1.0.0-beta.1","1.1.0","1.10.0","1.10.1","1.10.2","1.10.3","1.11.0","1.11.1","1.11.2","1.12.0","1.12.1","1.12.2","1.12.3","1.13.0","1.13.1","1.13.2","1.14.0","1.14.1","1.14.2","1.14.3","1.15.0","1.15.1","1.15.2","1.15.3","1.16.0","1.17.0","1.18.0","1.18.1","1.18.2","1.2.0","1.2.1","1.3.0","1.3.1","1.3.2","1.3.3","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.5.0","1.5.1","1.6.0","1.6.1","1.7.0","1.8.0","1.8.1","1.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-q7jx-v53g-848w/GHSA-q7jx-v53g-848w.json"}}],"schema_version":"1.9.0","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"}]}