CVE-2026-54787 sigstore-go fails to check signature timestamps against a signing key's validity period
Attackers can use expired signing keys to create valid signatures because the library fails to verify timestamps against key validity periods.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54787?
CVE-2026-54787 is a low-severity vulnerability in sigstore-go, published on 31 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-324
Which versions are affected by CVE-2026-54787?
3 open source packages ship an affected version, including github.com/sigstore/sigstore-go.
| Package | Affected | Fixed in |
|---|---|---|
github.com/sigstore/sigstore-go Go | All versions | 1.2.1 |
github.com/sigstore/sigstore-go Go | All versions | 1.2.1 |
github.com/sigstore/sigstore-go Go | All versions | 1.2.1 |
How do I fix CVE-2026-54787?
Upgrade github.com/sigstore/sigstore-go to 1.2.1 or later.
Is CVE-2026-54787 being exploited?
There is no known exploitation of CVE-2026-54787 in the wild and no public exploit code.
Sources
Also known as AZL-94425, CLEANSTART-2026-HF60121, DEBIAN-CVE-2026-54787, GHSA-wqqc-jjcq-vfxm, GO-2026-6162, MINI-229j-wj9j-43r5 and 69 more.