# CVE-2026-54787

## Summary

- **CVE ID:** CVE-2026-54787
- **Severity:** LOW
- **CVSS Score:** 3.1 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N)
- **CWE:** CWE-324
- **Published:** Jul 31, 2026
- **Last Modified:** Aug 1, 2026

## 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.

## Affected Products

- sigstore — sigstore-go (< 1.2.1)

## References

- [CNA](https://github.com/sigstore/sigstore-go/security/advisories/GHSA-wqqc-jjcq-vfxm)
- [CNA](https://github.com/sigstore/sigstore-go/pull/642)
- [CNA](https://github.com/sigstore/sigstore-go/commit/4594ab4c779d08be1f4419803a8249188f35ed5f)
- [CNA](https://github.com/sigstore/sigstore-go/releases/tag/v1.2.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.09%
- **EPSS Percentile:** 0.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._