CVE-2026-54787

sigstore-go fails to check signature timestamps against a signing key's validity period

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.

Affected

sigstore · sigstore-go

CVSS v3.1 GITHUB

3.1 LOWCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS

0.13% chance of exploitation in the next 30 days, 3rd percentile

Published

2026-07-31

Proof-of-concept exploits (1)

• advisories/GHSA-wqqc-jjcq-vfxm

References

• CVE Record
• NVD entry