CVE-2026-82757

ash_authentication_oauth2_server CIMD fetcher classifies IPv4-in-IPv6 and site-local addresses as public, allowing SSRF

Published: Sep 7, 2026Updated: Sep 8, 2026 Sources: CVE List NVDCWE-918

N/ACVSS

NVD MITRE

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.

No summary for this CVE yet.

Weaknesses

CWE-918

Affected Products

ash-project

oss-projectaka ash_authentication_phoenix, ash_postgres, ash

ash_authentication_oauth2_serverLibrary

OSS Libraries

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Attack Graph

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References

https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv

github.com

https://cna.erlef.org/cves/CVE-2026-82757.html

cna.erlef.org

https://osv.dev/vulnerability/EEF-CVE-2026-82757

osv.dev

and 1 more references View all →

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