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Improper Signature VerificationWeakness · CWE-347

CVE-2026-48758

MEDIUM · 5.4 CVSS v3.1 Published 2026-07-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
60/100
Remediation priority · Elevated
Remotely reachable Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The preAuthEncoding function in @sigstore/core uses Node.js ASCII encoding when converting the PAE (Pre-Authentication Encoding) string to bytes. This allows an attacker to mutate the payloadType after signing without invalidating the signature, breaking DSSE's type-binding guarantee.

MitigationUpgrade @sigstore/core to version 3.2.1 or later to address the encoding vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate @sigstore/core installation
    Run 'npm list @sigstore/core' or check package.json dependencies to confirm @sigstore/core is installed in your project
    Affected if @sigstore/core is not found in dependencies, the vulnerability does not apply
  2. Determine installed version
    Run 'npm list @sigstore/core' to retrieve the currently installed version number
    Affected if Version is below 3.2.1 (the fixed release)
  3. Verify preAuthEncoding usage
    Search project code for imports or calls to 'preAuthEncoding' from @sigstore/core, such as: import { preAuthEncoding } from '@sigstore/core'
    Affected if The function is imported and used in your codebase
  4. Inspect encoding implementation
    Examine the node_modules/@sigstore/core/dist/index.js or source file containing preAuthEncoding; look for uses of 'ascii' encoding in the conversion, for example: Buffer.from(paeString, 'ascii')
    Affected if The code uses ASCII encoding (not UTF-8) for the PAE conversion

You are affected if @sigstore/core versions below 3.2.1 are installed and the preAuthEncoding function with ASCII encoding is being used in your environment

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade @sigstore/core to version 3.2.1 or later to address the encoding vulnerability.

Recommended fix High confidence

@sigstore/core version 3.2.1

  1. Identify all dependencies that include @sigstore/core in your project (e.g., sigstore, @sigstore/sign, @sigstore/verify)
  2. Run 'npm list @sigstore/core' or 'yarn list @sigstore/core' to determine the currently installed version
  3. Update @sigstore/core to version 3.2.1 by running 'npm update @sigstore/[email protected]' or 'yarn upgrade @sigstore/[email protected]'
  4. If your project locks direct dependencies, update package.json to specify '@sigstore/core': '^3.2.1' and run 'npm install' or 'yarn install'
  5. Verify the upgrade was successful by running 'npm list @sigstore/core' and confirming version 3.2.1 or higher is installed
  6. Re-run your signature verification and signing workflows to confirm the vulnerability is resolved

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-48758 in production — separate from our analysis above.

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