Skip to content
Fencer Vulns
medium 5.9

CVE-2026-48595 json

Authorization header leaks to third-party origin on cross-origin redirect in Tesla.Middleware.FollowRedirects

published 2026-06-02 5 mo ago modified 2026-09-24 45 d ago also EEF-CVE-2026-48595 , GHSA-9m9w-gxf7-rh8m , EUVD-2026-34014

cvss
5.9
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

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 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.

Patch / fix

  • hex tesla 1.18.3
  • elixir-tesla tesla 1.18.3

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/elixir-tesla/tesla/security/advisories/GHSA-9m9w-gxf7-rh8m referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.2 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
CNA 4.0 8.2 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
hex tesla
>=0.6.0, <1.18.3
>=1.4.0, <1.18.3
1.18.3

Affected products

  • elixir-tesla tesla

Classification

Weakness
  • CWE-178 Improper Handling of Case Sensitivity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.