CVE-2026-82757 Details
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.
A Server-Side Request Forgery (SSRF) vulnerability exists in the ash-project ash_authentication_oauth2_server package, specifically in versions 0.3.0 prior to 0.3.1. This vulnerability allows an attacker who controls a client metadata URL and its DNS to manipulate the server into connecting to internal or loopback addresses. The issue arises because the outbound policy for CIMD metadata fetches incorrectly classifies certain IPv6 address forms, such as IPv4-compatible addresses and deprecated site-local addresses, as publicly routable. As a result, an attacker could exploit this misclassification to access spaces that the policy intended to block.
Users can update to ash_authentication_oauth2_server version 0.3.1, which addresses the vulnerability by correcting the address classification in the SSRF policy. Alternatively, restrict outbound egress from the server or disable the CIMD feature.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 7, 2026CISA-ADP
Assessed Sep 8, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://cna.erlef.org/cves/CVE-2026-82757.html | EEF | AdvisoryBundle |
| https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972 | EEF | Source CodeVendor |
| https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv | EEF | AdvisoryRemedyVendor |
| https://osv.dev/vulnerability/EEF-CVE-2026-82757 | EEF | AdvisoryBundle |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-918 | Server-Side Request Forgery (SSRF) | EEF |
Affected Products
| Product | Versions |
|---|---|
| ash-project ash_authentication_oauth2_server | >= 0.3.0, < 0.3.1 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 8, 2026 | CVE Modified | CISA-ADP |
| Sep 7, 2026 | New CVE Received | EEF |