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
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| ash-project | ash_authentication_oauth2_server | 0.3.0 – < 0.3.1 | 0.3.1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Hex | ash_authentication_oauth2_server | >= 0.3.0, < 0.3.1 | 0.3.1 | EEF-CVE-2026-82757 |
References
- https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv vendor-advisory related
- https://cna.erlef.org/cves/CVE-2026-82757.html related
- https://osv.dev/vulnerability/EEF-CVE-2026-82757 related
- https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972 patch