CVE-2026-82757: SSRF

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.

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EPSS — Exploit Prediction

0.0037

Probability of exploitation

0.30%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-918 Server-Side Request Forgery (SSRF)

References

Other 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

Frequently Asked Questions

What is CVE-2026-82757? +

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.

How do I check if I'm vulnerable to CVE-2026-82757? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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