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Insufficient Filename Validation in Client-Upload Signed-URL Endpoints

Moderate
denolfe published GHSA-frq9-7j6g-v74x Mar 30, 2026

Package

npm @payloadcms/storage-azure (npm)

Affected versions

< 3.78.0

Patched versions

3.78.0
npm @payloadcms/storage-gcs (npm)
< 3.78.0
3.78.0
npm @payloadcms/storage-r2 (npm)
< 3.78.0
3.78.0
npm @payloadcms/storage-s3 (npm)
< 3.78.0
3.78.0

Description

Impact

The client-upload signed-URL endpoints for S3, GCS, Azure, and R2 did not properly sanitize filenames. An attacker could craft filenames to escape the intended storage location.

You are affected if ALL of these are true:

  • Payload version < v3.78.0

  • Using client-upload signed-URL endpoints for any supported storage adapter

    Patches

This vulnerability has been patched in v3.78.0. Filename validation has been hardened for client uploads.

Users should upgrade to v3.78.0 or later.

Workarounds

Until you can upgrade:

  • Limit access to client-upload signed-URL endpoints to trusted users only.

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVE ID

CVE-2026-34750

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.