---
id: CVE-2026-82755
title: >-
  Use of Cache Containing Sensitive Information vulnerability in ash-project
  ash_authentication_oauth2_server allows a shared HTTP cache to serve one
  tenant's OAuth discovery metadata to another tenant's clients.


  The RFC 8414 and RFC 9728…
summary: >-
  Use of Cache Containing Sensitive Information vulnerability in ash-project
  ash_authentication_oauth2_server allows a shared HTTP cache to serve one
  tenant's OAuth discovery metadata to another tenant's clients.


  The RFC 8414 and RFC 9728…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N'
cwe:
  - CWE-524
vendor: ash-project
product: ash_authentication_oauth2_server
affected:
  - ash_authentication_oauth2_server >= 0.1.3 < 0.3.1
  - >-
    ash-project/ash_authentication_oauth2_server >=
    99de0a1cacb5ef667c4533278b7c81ca98c00231 <
    768d87f70e4e97ae1d2bf1606b5bf3f4d03f24a1
published: '2026-09-07'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T15:18:50.490'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82755'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-82755.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ash-project/ash_authentication_oauth2_server/commit/768d87f70e4e97ae1d2bf1606b5bf3f4d03f24a1
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-crqf-7m54-4hgc
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-82755'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T14:42:10.746522Z'
cvssSource: cna
epss: 0.00658
epssPercentile: 0.49382
ingestedAt: '2026-09-08T15:33:26.980Z'
---

## Overview

Use of Cache Containing Sensitive Information vulnerability in ash-project ash_authentication_oauth2_server allows a shared HTTP cache to serve one tenant's OAuth discovery metadata to another tenant's clients.

The RFC 8414 and RFC 9728 metadata endpoints in AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter return tenant-specific values (issuer, authorization_endpoint, token_endpoint, jwks_uri) when a tenant is set, but sent them with Cache-Control: public, max-age=3600 and no Vary. When the tenant is derived from something other than the URL (a header or the Host) and a shared cache sits in front, the cache key is the URL alone, so a stored response for one tenant is served to another for up to an hour. Affected clients may then send authorization codes and secrets to the wrong tenant's token endpoint and validate tokens against the wrong keys.

This issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.