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.

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Fixes

Solution

No solution given by the vendor.


Workaround

Normalize all header keys to lowercase before passing them to Tesla. Use "authorization" instead of "Authorization" when setting headers via Tesla.put_header/3 or Tesla.Middleware.Headers.

History

Wed, 03 Jun 2026 02:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Authorization header leaks to third-party origin on cross-origin redirect in Tesla.Middleware.FollowRedirects
First Time appeared Elixir-tesla
Elixir-tesla tesla
Weaknesses CWE-178
CPEs cpe:2.3:a:elixir-tesla:tesla:*:*:*:*:*:*:*:*
Vendors & Products Elixir-tesla
Elixir-tesla tesla
References
Metrics cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-06-02T19:12:24.989Z

Reserved: 2026-05-22T09:36:56.834Z

Link: CVE-2026-48595

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-06-02T20:16:38.390

Modified: 2026-06-02T20:16:38.390

Link: CVE-2026-48595

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-03T04:30:05Z

Weaknesses