# CVE-2026-124701: Deserialization of Untrusted Data in Progress Telerik UI for WinForms

> Attackers can exploit unsafe deserialization in Telerik UI for WinForms to perform unauthorized actions in affected applications.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Harmful if only installed:** No
- **Needs a specific call:** No
- **Fix available:** No
- **Published:** 12 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** GHSA-2gpg-hj59-w97r

## What is CVE-2026-124701?

CVE-2026-124701 is a high-severity unsafe deserialization vulnerability in Progress Software Telerik UI for WinForms, published on 12 Nov 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In Telerik UI for WinForms, versions prior to 2026.4.1111, a deserialization of untrusted data vulnerability exists that allows an attacker to perform unauthorized actions in the context of the affected application.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-124701?

An affected version is exposed as installed. No special setting or call is needed.


## How do I fix CVE-2026-124701?

No fix has been published for CVE-2026-124701 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-124701 being exploited?

There is no known exploitation of CVE-2026-124701 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-124701 and fix it if it is affected.

What it is: CVE-2026-124701 is a high-severity unsafe deserialization vulnerability in Progress Software Telerik UI for WinForms, published on 12 Nov 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-124701 in the wild and no public exploit code.
Exposure: An affected version is exposed as installed. No special setting or call is needed.

Affected product: Progress Software Telerik UI for WinForms. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-124701/ (Markdown: https://insights.sbomify.com/CVE-2026-124701/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-124701
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124701
- OSV: https://osv.dev/vulnerability/CVE-2026-124701

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-124701/
Summaries are generated and may contain mistakes; the official description above is the record.