sigstore-go is a Go library for Sigstore signing and verification. Prior to 1.2.1, sigstore-go does not check a bundle signing timestamp against the validity window of an ExpiringKey wrapping a self-managed long-lived signing key without a certificate, which can allow an attacker holding expired key material to sign accepted bundles. This issue is fixed in version 1.2.1.
https://github.com/sigstore/sigstore-go/security/advisories/GHSA-wqqc-jjcq-vfxm
https://github.com/sigstore/sigstore-go/releases/tag/v1.2.1
https://github.com/sigstore/sigstore-go/pull/642
https://github.com/sigstore/sigstore-go/commit/4594ab4c779d08be1f4419803a8249188f35ed5f