CVE-2026-49478 sigstore CVE debrief

Who should care

Organizations using Fulcio for code signing certificates, particularly those with OpenID Connect (OIDC) identity integrations and Kubernetes ServiceAccount management, should be aware of this vulnerability. The affected versions may allow malicious actors to perform unauthorized actions or access sensitive information. Upgrading to version 1.8.6 or later is recommended to mitigate this vulnerability. Additionally, organizations should review their ServiceAccount token management and OIDC discovery processes to ensure they are not exposed to potential attacks. Security teams and vulnerability management teams should prioritize this update and assess their current deployments for potential exposure. Monitoring for suspicious OIDC discovery activity is also recommended. Asset inventory and platform teams may need to review affected deployments and coordinate with security teams for remediation. Rollback/change windows may be necessary to apply the patch without disrupting operations. Source tracking and compensating controls can help mitigate the risk while remediation is in progress. Vendor patch guidance should be followed closely to ensure a smooth and secure update process. Exposure review and monitoring can help detect potential attacks. Asset inventory and platform teams may need to review affected deployments and coordinate with security teams for remediation. Rollback/change windows may be necessary to apply the patch without disrupting operations. Source tracking and compensating controls can help mitigate the risk while remediation is in progress. Vendor patch guidance should be followed closely to ensure a smooth and secure update process. Exposure review and monitoring can help detect potential attacks. Asset inventory and platform teams may need to review affected deployments and coordinate with security teams for remediation. Rollback/change windows may be necessary to apply the patch without disrupting operations. Source tracking and compensating controls can help mitigate the risk while remediation is in progress. Vendor patch guidance should be followed closely to ensure a smooth and secure update process. Exposure review and monitoring can help in

Technical summary

Fulcio versions through 1.8.5 improperly follow cross-host redirects and attach Kubernetes ServiceAccount tokens during OIDC discovery. This improper handling allows a malicious or compromised issuer to perform blind SSRF, substitute and cache malicious JWKS keys, or disclose ServiceAccount tokens to external hosts. The vulnerability is addressed in version 1.8.6, which blocks cross-host redirects, restricts token injection, and restricts local token loading.

Defensive priority

Organizations using Fulcio for code signing certificates should prioritize upgrading to version 1.8.6 to block cross-host redirects, restrict token injection, and restrict local token loading.

Recommended defensive actions

• Upgrade to Fulcio version 1.8.6 or later
• Restrict token injection and local token loading
• Monitor for suspicious OIDC discovery activity
• Review and update ServiceAccount token management
• Perform exposure review for potential attacks
• Implement compensating controls for exposed systems
• Track exceptions and retest remediated assets

Evidence notes

Evidence from the NVD and CVE.org indicates that Fulcio versions through 1.8.5 are vulnerable to blind SSRF, JWKS key substitution, and ServiceAccount token disclosure due to improper handling of cross-host redirects and Kubernetes ServiceAccount tokens during OIDC discovery. The vulnerability allows a malicious or compromised issuer to perform these attacks, potentially disclosing ServiceAccount tokens to external hosts or substituting and caching malicious JWKS keys. Organizations should verify their Fulcio deployments and consider the potential impact on their systems.

Official resources