Core: CWE-347: Improper Verification of Cryptographic Signature in sigstore sigstore-js (CVE-2026-48758)
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.
AI Analysis
Technical Summary
A vulnerability exists in the @sigstore/core package's preAuthEncoding function where the use of Node.js 'ascii' encoding truncates characters above U+00FF, allowing Unicode characters to produce the same encoded bytes as ASCII characters. This flaw permits mutation of the DSSE payloadType after signing without invalidating the signature, violating the DSSE type-binding guarantee. The issue affects all versions before 3.2.1.
Potential Impact
An attacker with limited privileges (PR:L) can modify the DSSE payloadType after signing without invalidating the signature, potentially leading to integrity issues. The vulnerability does not impact confidentiality but can affect the integrity and availability of the signed data. No known exploits are reported in the wild.
Mitigation Recommendations
A fix is available in version 3.2.1 of @sigstore/core. Users should upgrade to version 3.2.1 or later to remediate this vulnerability. No other mitigations are indicated.
Core: CWE-347: Improper Verification of Cryptographic Signature in sigstore sigstore-js (CVE-2026-48758)
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 v3.1
Score 5.4medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
A vulnerability exists in the @sigstore/core package's preAuthEncoding function where the use of Node.js 'ascii' encoding truncates characters above U+00FF, allowing Unicode characters to produce the same encoded bytes as ASCII characters. This flaw permits mutation of the DSSE payloadType after signing without invalidating the signature, violating the DSSE type-binding guarantee. The issue affects all versions before 3.2.1.
Potential Impact
An attacker with limited privileges (PR:L) can modify the DSSE payloadType after signing without invalidating the signature, potentially leading to integrity issues. The vulnerability does not impact confidentiality but can affect the integrity and availability of the signed data. No known exploits are reported in the wild.
Mitigation Recommendations
A fix is available in version 3.2.1 of @sigstore/core. Users should upgrade to version 3.2.1 or later to remediate this vulnerability. No other mitigations are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-jfc7-64v2-mr8c
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-48758"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6a3ef78d27e9c79719ff493d
Added to database: 06/26/2026, 22:05:01 UTC
Last enriched: 07/15/2026, 07:56:26 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 129
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