---
id: CVE-2026-82757
title: >-
  Server-Side Request Forgery (SSRF) vulnerability in ash-project
  ash_authentication_oauth2_server allows an attacker who controls a client
  metadata URL and its DNS to make the server connect to internal or loopback
  addresses.


  public_ip?/…
summary: >-
  Server-Side Request Forgery (SSRF) vulnerability in ash-project
  ash_authentication_oauth2_server allows an attacker who controls a client
  metadata URL and its DNS to make the server connect to internal or loopback
  addresses.


  public_ip?/…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N'
cwe:
  - CWE-918
vendor: ash-project
product: ash_authentication_oauth2_server
affected:
  - ash_authentication_oauth2_server >= 0.3.0 < 0.3.1
  - >-
    ash-project/ash_authentication_oauth2_server >=
    e713a9ba816761140c226e2ca55b75c0b93f5984 <
    268b591261a3473ab9b87272963e4dd2fd99d972
published: '2026-09-07'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T15:18:50.823'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82757'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-82757.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-82757'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T14:43:50.818031Z'
cvssSource: cna
epss: 0.00665
epssPercentile: 0.49647
ingestedAt: '2026-09-08T15:33:26.980Z'
---

## Overview

Server-Side Request Forgery (SSRF) vulnerability in ash-project ash_authentication_oauth2_server allows an attacker who controls a client metadata URL and its DNS to make the server connect to internal or loopback addresses.

public_ip?/1 in AshAuthentication.Oauth2Server.CIMD.ReqFetcher enforces the outbound policy for CIMD metadata fetches. It classified several address forms as publicly routable that are not: IPv4-compatible ::/96 (for example ::127.0.0.1), SIIT IPv4-translated ::ffff:0:0:0/96, and deprecated site-local fec0::/10. A returned AAAA record in one of these ranges passed the policy, so a fetch pinned to that address reached space the policy was meant to block.

This issue affects ash_authentication_oauth2_server: from 0.3.0 before 0.3.1.

## Remediation

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