CVE-2026-118763 sigstore CVE debrief

Who should care

Defenders responsible for managing dependencies in their environments, particularly those using @sigstore/oci, should be aware of this vulnerability. They should verify the affected versions in their systems and update to a fixed version to prevent potential misuse of the Authorization header.

Why it matters

The vulnerability in @sigstore/oci allows for potential misuse of the Authorization header, leading to unauthorized access and data breaches. Defenders should verify affected versions and update to a fixed version to mitigate these risks.

• Potential unauthorized access to blob storage due to misuse of the Authorization header.
• Possible data breaches resulting from cross-host blob-upload requests.
• Need for verification of affected versions and updating to a fixed version.
• Potential for lateral movement within the environment if not properly mitigated.

Technical summary

The @sigstore/oci package has a vulnerability where it sends the registry Authorization header to a cross-host blob-upload Location. This occurs because the `signIn()` function sets the Authorization header as a default for the shared client, which is then used for requests to different hosts without proper validation. The issue is confirmed in sigstore-js at commit `3a83271`. The `signIn()` function sets the Authorization header via `.defaults()`, which is then attached to every request the client issues, including requests to different hosts. The `uploadBlob()` function reads the `Location` response header and builds the `uploadLocation` without checking if the host or scheme matches the registry host. This

Defensive priority

Defenders should prioritize verifying the affected versions of @sigstore/oci in their environments and updating to version 0.7.2 or later. They should also review their systems for any potential misuse of the Authorization header.

Recommended defensive actions

• Verify the version of @sigstore/oci in your environment and update to 0.7.2 or later if necessary.
• Review system configurations for potential misuse of the Authorization header.
• Monitor for any suspicious activity related to blob uploads.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The issue is confirmed in sigstore-js at commit `3a83271`. The `signIn()` function sets the Authorization header via `.defaults()`, which is then attached to every request the client issues, including requests to different hosts. The `uploadBlob()` function reads the `Location` response header and builds the `uploadLocation` without checking if the host or scheme matches the registry host.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.