CVE-2026-31830 sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest
Attackers can bypass signature verification in sigstore-ruby by providing mismatched artifact digests, allowing unsigned or tampered code to appear valid.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31830?
CVE-2026-31830 is a high-severity vulnerability in sigstore-ruby, published on 10 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
sigstore-ruby is a pure Ruby implementation of the sigstore verify command from the sigstore/cosign project. Prior to 0.2.3, Sigstore::Verifier#verify does not propagate the VerificationFailure returned by verify_in_toto when the artifact digest does not match the digest in the in-toto attestation subject. As a result, verification of DSSE bundles containing in-toto statements returns VerificationSuccess regardless of whether the artifact matches the attested subject. This vulnerability is fixed in 0.2.3.
Weakness: CWE-252
Which versions are affected by CVE-2026-31830?
2 open source packages ship an affected version, including sigstore. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
sigstore RubyGems | All versions | 0.2.3 |
sigstore RubyGems | All versions | 0.2.3 |
Products include Sigstore Sigstore.
How do I fix CVE-2026-31830?
Upgrade sigstore to 0.2.3 or later.
Is CVE-2026-31830 being exploited?
There is no known exploitation of CVE-2026-31830 in the wild and no public exploit code.
Sources
Also known as GHSA-mhg6-2q2v-9h2c.