CVE-2026-13186
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 · uneditedIn Progress® Telerik® UI for AJAX prior to v2026.2.708, a path traversal vulnerability in the file-based persistence storage provider can be exploited when the storage key is derived from user-controlled input, enabling attacker-controlled deserialization and remote code execution.
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 confidenceThis is a path traversal vulnerability in Telerik UI for AJAX's file-based persistence storage provider. When storage keys are derived from user-controlled input, attackers can manipulate the key to traverse directories and achieve attacker-controlled deserialization, leading to remote code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 2013.1.220, < 2026.2.708CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Telerik UI for AJAX versionCheck the assembly version of Telerik.Web.UI.dll in the bin folder, or look for the Telerik NuGet package version in packages.config or .csproj, or examine the Telerik assembly reference in web.configAffected if the version is lower than v2026.2.708 (e.g., v2025.x, v2024.x, earlier)
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Confirm file-based persistence provider is in useExamine the web.config for RadCompression settings or custom persistence provider configuration. Look for classes inheriting from FileBasedStorageProvider or similar file-based storage implementations in the codebaseAffected if file-based persistence storage is configured and enabled in the application
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Check if storage keys derive from user inputSearch code for instances where Telerik's storage API (such as RadCompression or session/state storage) uses Request parameters, query strings, headers, or cookies directly as storage keys without sanitizationAffected if storage keys are constructed from user-controlled input like Request.QueryString, Request.Form, or similar sources without validation
You are affected if your Telerik UI for AJAX version is prior to v2026.2.708 AND you use file-based persistence with storage keys derived from user input.
Generated from the published advisory. Verify against your own configuration.
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 · scoped2026.2.708
Upgrade to Telerik UI for AJAX v2026.2.708 or later. Additionally, ensure storage keys are not derived from user-controlled input and implement proper input validation.
v2026.2.708 or later
- 1. Identify the current version of Telerik UI for AJAX in use by checking the assembly version or NuGet package reference
- 2. Upgrade to Telerik UI for AJAX v2026.2.708 or later by updating the NuGet package reference
- 3. After upgrading, review the file-based persistence storage provider configuration to ensure storage keys are not derived from user-controlled input
- 4. Test the application thoroughly to verify the upgrade does not break existing functionality
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-13186 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-13186 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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