CVE-2026-34750: Payload has Insufficient Filename Validation in Client-Upload Signed-URL Endpoints
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.
Consumers 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.
Consumers should upgrade to v3.78.0 or later.
Workarounds
Consumers can upgrade:
- Limit access to client-upload signed-URL endpoints to trusted users only.
Other sources
Payload is a free and open source headless content management system. Prior to version 3.78.0 in @payloadcms/storage-azure, @payloadcms/storage-gcs, @payloadcms/storage-r2, and @payloadcms/storage-s3, 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. This issue has been patched in version 3.78.0 for @payloadcms/storage-azure, @payloadcms/storage-gcs, @payloadcms/storage-r2, and @payloadcms/storage-s3.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-34750?
The severity of CVE-2026-34750 is considered high due to its potential to allow attackers to manipulate file paths.
How do I fix CVE-2026-34750?
To fix CVE-2026-34750, update to version 3.78.0 or later of the affected packages.
Which systems are affected by CVE-2026-34750?
CVE-2026-34750 affects systems using @payloadcms/storage-s3, @payloadcms/storage-r2, @payloadcms/storage-gcs, and @payloadcms/storage-azure versions below 3.78.0.
What type of attack does CVE-2026-34750 allow?
CVE-2026-34750 allows attackers to craft filenames that could escape the intended storage location, potentially accessing unauthorized data.
What platforms are involved in CVE-2026-34750?
CVE-2026-34750 involves platforms such as S3, GCS, Azure, and R2 through the Vulnerable payload CMS endpoints.