Exploited. On CISA's list since 2021-11-03, and used by ransomware.

Accellion FTA Server-Side Request Forgery (SSRF) Vulnerability

CVE-2021-27103 · Accellion FTA · Published 2021-02-16

How bad would it be?

9.8 out of 10

CVSS rates it critical: about as damaging as flaws get.

How likely is it to be used?

11%

Estimated chance of exploitation in the next 30 days, higher than 95% of all scored flaws (EPSS, 2026-10-29).

Is it already being used?

Yes

CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 1808 days ago (2021-11-17).

What CISA says to do

Apply updates per vendor instructions.

Accellion FTA contains a server-side request forgery (SSRF) vulnerability exploited via a crafted POST request to wmProgressstat.html.

nvd.nist.gov

What the flaw is

Accellion FTA 9_12_411 and earlier is affected by SSRF via a crafted POST request to wmProgressstat.html. The fixed version is FTA_9_12_416 and later.

From the NVD.

Learn this

Explore this week’s weaknesses and all learning topics

Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.

Server-side request forgery

Input makes a server send a request to an unintended destination.

CWE-918 · CISA KEV; NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0; NVD record: nvd@nist.gov

Reading and practice labs · Free account for labs. Basic HTTP knowledge; some labs use Burp Suite.

Explore the labs at PortSwigger Web Security Academy How it is prevented

CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.

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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.