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Secures the outbound OIDC discovery request flow against SSRF, JWKS substitution, and credential leakage. Blocks cross-host redirects: Configures a custom CheckRedirect callback on all OIDC discovery clients to reject redirects that attempt to leave the original issuer's host boundary. SSRF was previously mitigated by adding anchors to the meta issuer regex, but this was not a complete mitigation since a malicious meta issuer could specify an HTTP redirect, which the Go HTTP client would follow by default. Restricts bearer token injection: Updates bearerTokenTransport to only attach the Kubernetes service-account bearer token when the outgoing request destination host exactly matches the expected issuer's host. This prevents token leakage during both redirect scenarios and cross-host JWKS URIs. Signed-off-by: Hayden <8418760+Hayden-IO@users.noreply.github.com>
bobcallaway
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May 26, 2026
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May 29, 2026
…ath (#2356) Gate the in-cluster CA + bearer-token attachment in httpClientForIssuer on the issuer being directly listed in OIDCIssuers, in addition to the existing match against k8sIssuerURL. Clusters whose --service-account-issuer is not literally https://kubernetes.default.svc (e.g. K3s, which uses https://kubernetes.default.svc.cluster.local) can again use the in-cluster auth path when their issuer URL is explicitly listed in OIDCIssuers. The SSRF/token-leak protection from #2354 is preserved: MetaIssuer wildcard matches against attacker-controlled hosts still do not receive the bearer token, because the new gate trusts only directly-listed OIDCIssuers entries (and the default k8sIssuerURL itself). Fixes #2355. Signed-off-by: Kevin Monroe <kevin.monroe@chainguard.dev>
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Secures the outbound OIDC discovery request flow against SSRF, JWKS substitution, and credential leakage.
Blocks cross-host redirects: Configures a custom CheckRedirect callback on all OIDC discovery clients to reject redirects that attempt to leave the original issuer's host boundary. SSRF was previously mitigated by adding anchors to the meta issuer regex, but this was not a complete mitigation since a malicious meta issuer could specify an HTTP redirect, which the Go HTTP client would follow by default.
Restricts bearer token injection: Updates bearerTokenTransport to only attach the Kubernetes service-account bearer token when the outgoing request destination host exactly matches the expected issuer's host. This prevents token leakage during both redirect scenarios and cross-host JWKS URIs.
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