CVE-2019-18935
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 · uneditedProgress Telerik UI for ASP.NET AJAX through 2019.3.1023 contains a .NET deserialization vulnerability in the RadAsyncUpload function. This is exploitable when the encryption keys are known due to the presence of CVE-2017-11317 or CVE-2017-11357, or other means. Exploitation can result in remote code execution. (As of 2020.1.114, a default setting prevents the exploit. In 2019.3.1023, but not earlier versions, a non-default setting can prevent exploitation.)
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 confidenceProgress Telerik UI for ASP.NET AJAX contains a .NET deserialization vulnerability in the RadAsyncUpload function. When encryption keys are known (due to CVE-2017-11317/CVE-2017-11357 or other means), attackers can deserialize malicious objects leading to remote code execution. Version 2020.1.114 introduced a default setting that prevents exploitation.
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>= 2011.1.315, <= 2020.1.114CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/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.
-
Locate the Telerik.Web.UI.dll fileSearch for Telerik.Web.UI.dll in the web application's bin directory or installed program files. Right-click the DLL, select Properties, and view the Details tab to find the File Version.Affected if The file version falls within the range 2011.1.315.0 through 2020.1.114.0 (or product version 2011.1.315 through 2020.1.114)
-
Check web.config for RadAsyncUpload handler registrationOpen the web.config file and search for 'RadAsyncUpload' or Telerik.Web.UI.WebResource. Look for entries under <system.webServer><handlers> that register the Telerik async upload handler.Affected if The handler is registered and enabled (not commented out or removed)
-
Verify the encryption key configurationSearch the web.config file for 'EncryptionKey' or 'ValidationKey' under the Telerik.Web.UI or machineKey section. The default keys from CVE-2017-11317 and CVE-2017-11357 may still be present.Affected if The encryption key is set to a known default value or is absent, leaving the deserialization vulnerable to weaponized payloads
-
Check the DisableHandler configuration settingSearch web.config for 'Telerik.AsyncUpload.DisableHandler' or similar Telerik configuration settings. The 2019.3.1023 and later versions introduced a non-default setting to block exploitation.Affected if The DisableHandler setting is absent, set to false, or not configured, meaning the RadAsyncUpload handler remains exploitable
A defender is affected if Telerik UI for ASP.NET AJAX version 2020.1.114 or earlier is installed, the RadAsyncUpload handler is enabled in web.config, and the encryption key is not properly randomized or the DisableHandler mitigation is not configured.
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 · scopedUpgrade to Telerik UI for ASP.NET AJAX version 2020.1.114 or later where the default configuration blocks the exploit. For version 2019.3.1023, apply the documented non-default configuration setting to mitigate. Also investigate potential key compromise from CVE-2017-11317/11357.
2020.1.114 or later (recommend latest stable release)
- 1. Identify the current version of Telerik UI for ASP.NET AJAX in use by checking the Bin folder for Telerik.Web.UI.dll and viewing its properties, or by searching for 'Telerik.Web.UI' in the project references
- 2. If the current version is 2020.1.114 or later, verify that the default setting 'DisableHandler' is enabled (this should be the default in 2020.1.114+)
- 3. If the current version is between 2011.1.315 and 2020.1.113, upgrade to version 2020.1.114 or later
- 4. After upgrade, verify the fix by confirming the RadAsyncUpload handler is properly secured and encryption keys have been rotated
- 5. Also address the related CVEs (CVE-2017-11317 and CVE-2017-11357) by ensuring encryption keys are rotated and not using default keys
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-18935 — 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-2019-18935 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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
- No spam, self-promotion, credentials, or personal data