CVE-2026-48758

Deferred Deferred - Pending Action

Pre-Authentication Encoding Bypass in Sigstore-js

Publication date: 2026-07-14

Last updated on: 2026-07-15

Assigner: GitHub, Inc.

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-07-14

Last Modified

2026-07-15

Generated

2026-08-04

AI Q&A

2026-07-15

EPSS Evaluated

2026-08-02

NVD

CVE-2026-48758

Affected Vendors & Products

Vendor	Product	Version / Range
sigstore	sigstore-js	to 3.2.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-347	The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Attack-Flow Graph

Executive Summary

The vulnerability in sigstore-js before version 3.2.1 involves the preAuthEncoding function using Node.js ASCII encoding to convert the PAE string to bytes. This allows the payloadType to be altered after signing without invalidating the signature, breaking the type-binding guarantee that DSSE is designed to provide.

Detection Guidance

Detection requires checking the version of sigstore-js in use. Run 'npm list @sigstore/core' or inspect package.json to verify if the version is below 3.2.1. If so, the system is vulnerable.

Impact Analysis

This vulnerability could allow an attacker to modify the payloadType after signing, potentially leading to unauthorized changes in signed data without detection. This undermines the integrity of signatures and could result in false trust in tampered data.

Compliance Impact

This vulnerability may impact compliance by undermining data integrity and non-repudiation guarantees required by standards like GDPR and HIPAA. If signatures can be altered without detection, it could lead to unauthorized data changes going unnoticed, violating compliance requirements for secure data handling.

Mitigation Strategies

Upgrade sigstore-js to version 3.2.1 or later using 'npm update @sigstore/core'. If direct upgrade is not possible, review and update dependencies to ensure compatibility with the patched version.

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