CVE-2026-48791 is a low-severity (CVSS 2) CWE-347 vulnerability in dev.sigstore:sigstore-java. O3 Security confirms whether CVE-2026-48791 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Sigstore Java has a vulnerability with bundle verification of integratedTime
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48791.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-48791 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
dev.sigstore:sigstore-javaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
sigstore-java is a sigstore java client for interacting with sigstore infrastructure. Version 2.0.0 erroneously removed verification of the integrated (Rekor entry) time) against the Fulcio certificate. Version 2.1.0 re-added this verification with enhancements that adhere to the Sigstore verification spec. The old sigstore-conformance test for this check was built incorrectly. This vulnerability impacts only users verifying bundles with dev.sigstore:sigstore-java:2.0.0. Older versions are not affected; it is fixed in dev.sigstore:sigstore-java:2.1.0 A malicious actor may exploit this if they were able to access a users system and exfiltrate the temporary private key used during signing and then reuse an old fulcio certificate later without requiring direct access to the user's credentials. Users may protect themselves by re-verifying their artifacts using the newest sigstore-java or another current sigstore client. Transparency logs may also be audited for unauthorized signatures for a suspected reused identity.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | dev.sigstore:sigstore-java | ≥ 2.0.0&&< 2.1.0 | 2.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dev.sigstore:sigstore-java. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update dev.sigstore:sigstore-java to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48791 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-48791 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-48791. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-48791 in your dependencies?
O3 detects CVE-2026-48791 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.