CVSS 4.0
6.3 mediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:NCVE-2026-82757
Medium (6.3). EPSS 0.7% chance of exploitation in the next 30 days.
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.
Severity
- EPSS
- 0.7% chance of exploitation in the next 30 days; higher than 51% of CVEs (scores of 2026-10-31)
- CWE
- CWE-918
- Published
- Modified
- Record from
- the NVD, synced
References
- https://cna.erlef.org/cves/CVE-2026-82757.html
- https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972
- https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv
- https://osv.dev/vulnerability/EEF-CVE-2026-82757