CVE-2026-48758 sigstore-js: DSSE payloadType type-binding failure
Attackers can mutate payload types after signing without invalidating signatures, breaking DSSE type-binding guarantees in sigstore-js.
- 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-2026-48758?
CVE-2026-48758 is a medium-severity vulnerability in sigstore-js, published on 14 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
sigstore-js provides JavaScript libraries for interacting with Sigstore services. Prior to 3.2.1, the preAuthEncoding function in @sigstore/core uses Node.js ascii encoding when converting the PAE string to bytes, allowing payloadType to be mutated after signing without invalidating the signature and breaking the type-binding guarantee that DSSE is designed to provide. This issue is fixed in version 3.2.1.
Weakness: CWE-347
Which versions are affected by CVE-2026-48758?
2 open source packages ship an affected version, including @sigstore/core.
| Package | Affected | Fixed in |
|---|---|---|
@sigstore/core npm | All versions | 3.2.1 |
@sigstore/core npm | All versions | 3.2.1 |
How do I fix CVE-2026-48758?
Upgrade @sigstore/core to 3.2.1 or later.
Is CVE-2026-48758 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48758 exists.
Sources
Also known as CLEANSTART-2026-BS35481, CLEANSTART-2026-FS67325, CLSA-2026-1790597352, CLSA-2026-1792603628, CLSA-2026-1793143332, GHSA-jfc7-64v2-mr8c and 8 more.