# CVE-2026-82757

## Summary

- **CVE ID:** CVE-2026-82757
- **Severity:** MEDIUM
- **CVSS Score:** 6.3 (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
- **Published:** Sep 7, 2026
- **Last Modified:** Sep 8, 2026

## Description

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.

## Affected Products

- ash-project — ash_authentication_oauth2_server (0.3.0)
- ash-project — ash_authentication_oauth2_server (e713a9ba816761140c226e2ca55b75c0b93f5984)

## References

- [CNA](https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv)
- [CNA](https://cna.erlef.org/cves/CVE-2026-82757.html)
- [CNA](https://osv.dev/vulnerability/EEF-CVE-2026-82757)
- [CNA](https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.37%
- **EPSS Percentile:** 30.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._