CVE-2024-53267: 
Java vulnerability analysis and mitigation

sigstore-java, a sigstore java client for interacting with sigstore infrastructure, has insufficient verification for validly-signed but "mismatched" bundles presented as proof of inclusion into a transparency log. This vulnerability (CVE-2024-53267) was discovered in version 1.0.0 and affects clients using any variation of KeylessVerifier.verify(). The issue was patched in version 1.1.0 (GitHub Advisory).

The vulnerability allows the verifier to accept a bundle with an unrelated log entry, where it cryptographically verifies everything but fails to ensure the log entry applies to the artifact in question. This enables "verifying" a bundle without actual proof that the signing event was logged. The issue stems from insufficient validation of the relationship between the bundle's contents and the transparency log entry (GitHub Advisory).

An attacker can create a bundle without a fulcio certificate and private key, combined with an unrelated but time-correct log entry to fake logging of a signing event. While the signer's identity remains available to the verifier and the signature must still be valid for the correct artifact, this could be used by malicious actors with compromised identities to prevent discovery via rekor's log monitors (GitHub Advisory).

The vulnerability has a CVSS v3.1 base score of 5.5 (Medium) with vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N. The attack requires local access and low privileges to execute (GitHub Advisory).

The vulnerability has been patched in version 1.1.0 with PR #856. Users are advised to upgrade to this version. For those unable to upgrade immediately, workarounds include recreating the log entry and comparing it to the provided log entry, or contacting the log to verify if the artifact signing event has been added (GitHub Advisory).