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5.9
Telerik UI for AJAX versions before 2026.1.225: Predictable file upload IDs
CVE-2026-2878
Summary
Old versions of Telerik UI for AJAX have a security issue that makes it possible for attackers to guess the names of uploaded files. This could allow them to tamper with or replace files uploaded by others. Update to version 2026.1.225 or later to fix this issue.
What to do
No fix is available yet. Check with your software vendor for updates.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| progress | telerik_ui_for_asp.net_ajax | <= 2026.1.225 | – |
Original title
In Progress® Telerik® UI for AJAX, versions prior to 2026.1.225, an insufficient entropy vulnerability exists in RadAsyncUpload, where a predictable temporary identifier, based on timestamp and fil...
Original description
In Progress® Telerik® UI for AJAX, versions prior to 2026.1.225, an insufficient entropy vulnerability exists in RadAsyncUpload, where a predictable temporary identifier, based on timestamp and filename, can enable collisions and file content tampering.
nvd CVSS3.1
5.9
Vulnerability type
CWE-331
- https://www.telerik.com/products/aspnet-ajax/documentation/knowledge-base/kb-sec... Mitigation Vendor Advisory
Published: 25 Feb 2026 · Updated: 12 Mar 2026 · First seen: 6 Mar 2026