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Fencer Vulns
critical 9.8

CVE-2021-28141 json

An issue was discovered in Progress Telerik UI for ASP.NET AJAX 2021.1.224.

published 2021-03-11 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-14840

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

An issue was discovered in Progress Telerik UI for ASP.NET AJAX 2021.1.224. It allows unauthorized access to MicrosoftAjax.js through the Telerik.Web.UI.WebResource.axd file. This may allow the attacker to gain unauthorized access to the server and execute code. To exploit, one must use the parameter _TSM_HiddenField_ and inject a command at the end of the URI. NOTE: the vendor states that this is not a vulnerability. The request's output does not indicate that a "true" command was executed on the server, and the request's output does not leak any private source code or data from the server

Exploit prediction

2.32% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • pastebin.com https://pastebin.com/JULpfvFJ referenced PoC, tagged "exploit" by a source, unverified
  • gist.github.com https://gist.github.com/shreyasfegade/e2480e26b2ed1d0c7175ecf7cb15f9c1 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.