---
id: CVE-2026-48595
title: >-
  Improper Handling of Case Sensitivity vulnerability in elixir-tesla tesla
  allows credential leakage to a third-party origin on cross-origin redirects.


  Tesla.Middleware.FollowRedirects strips security-sensitive headers on
  cross-origin re…
summary: >-
  Improper Handling of Case Sensitivity vulnerability in elixir-tesla tesla
  allows credential leakage to a third-party origin on cross-origin redirects.


  Tesla.Middleware.FollowRedirects strips security-sensitive headers on
  cross-origin re…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-178
vendor: elixir-tesla
product: tesla
affected:
  - 'tesla >= 1.4.0, < 1.18.3'
patched:
  - tesla 1.18.3
published: '2026-06-02'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:17:13.173'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48595'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-48595.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-tesla/tesla/commit/2d937d5813d7cda5cd726f41824985fb655c920f
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-tesla/tesla/commit/db963dba67651b9abd1fc420a1d9679cf6efe182
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-tesla/tesla/security/advisories/GHSA-9m9w-gxf7-rh8m
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-48595'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-tesla/tesla/security/advisories/GHSA-9m9w-gxf7-rh8m
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48595'
  - url: 'https://github.com/advisories/GHSA-9m9w-gxf7-rh8m'
tags:
  - nvd
  - cve.org
  - exploit-available
  - ghsa
  - erlang
  - score-dispute
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-03T15:59:45.683092Z'
scores:
  nvd: 5.9
  cna: 8.2
epss: 0.00487
epssPercentile: 0.4172
aliases:
  - GHSA-9m9w-gxf7-rh8m
ecosystem: erlang
ingestedAt: '2026-07-10T00:54:12.237Z'
---

## Overview

Improper Handling of Case Sensitivity vulnerability in elixir-tesla tesla allows credential leakage to a third-party origin on cross-origin redirects.

Tesla.Middleware.FollowRedirects strips security-sensitive headers on cross-origin redirects using a case-sensitive string comparison against a lowercase filter list (@filter_headers ["authorization", "host"]). HTTP header names are case-insensitive per RFC 7230, but Tesla preserves header keys verbatim as supplied by the caller without normalizing case. A header set as {"Authorization", "Bearer …"} (the RFC 7235 canonical casing used by virtually all HTTP libraries and documentation) does not match the lowercase filter entry and is forwarded to the redirect destination. An attacker who can control or influence a Location: response seen by the client (via their own endpoint, a redirect-open upstream, or a compromised origin) receives the bearer token or other Authorization material on the cross-origin request.

This issue affects tesla: from 1.4.0 before 1.18.3.

## Affected

- `tesla >= 1.4.0, < 1.18.3`

## Remediation

Upgrade past the affected range:

- `tesla 1.18.3`

## Package advisory (CVE-2026-48595)

Affected packages:

- `tesla >= 0.6.0, < 1.18.3`

Patched in:

- `tesla 1.18.3`

Source: https://github.com/advisories/GHSA-9m9w-gxf7-rh8m