oras-go: Malicious registry can hijack Bearer token realm to exfiltrate credentials and refresh tokens

oras-go is a Go library for managing OCI artifacts. Prior to 2.6.1, auth.Client follows the realm URL from a registry's WWW-Authenticate: Bearer challenge without validating the scheme or host, allowing a malicious or compromised registry to cause SSRF to internal networks such as http://169.254.169.254/, http://10.0.0.x/, and http://127.0.0.1/, or to downgrade a registry contacted over https:// to an http:// token endpoint in registry/remote/auth/client.go through Client.Do(), Client.fetchBearerToken(), fetchDistributionToken, and fetchOAuth2Token. This issue is fixed in version 2.6.1.

Source published

17 Jul 2026 19:34:53 UTC

Source modified

21 Jul 2026 02:06:49 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 2.1 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N