CVE-2021-27104
CriticalExploitedPublic exploitAccellion FTA 9_12_370 and earlier is affected by OS command execution via a crafted POST request to various admin endpoints.
Published Feb 16, 2021 · Updated Nov 3, 2025
Key Facts
Patch immediately- CVE-2021-27104 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Fta (Accellion).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 13, 2021 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 57% probability of exploitation in the next 30 days.
- Fixed versions are available, including Fta <=9_12_370, Fta 9_12_370.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
57%
Higher than 99.0% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
Accellion FTA 9_12_370 and earlier is affected by OS command execution via a crafted POST request to various admin endpoints. The fixed version is FTA_9_12_380 and later.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| Industry KEV feed | Apr 13, 2021 | Nov 17, 2021 | Known |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
1 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| FtaAccellion | See advisory | 9_12_370 |
Patched Releases
Fta
<=9_12_370
Timeline
Publicly disclosed
Feb 16, 2021
Added to Industry KEV feed
Apr 13, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Nov 3, 2025
Weakness Type
- CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
References
- advisoryhttps://github.com/accellion/CVEs/blob/main/CVE-2021-27104.txt
- advisoryhttps://www.accellion.com/products/fta/
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Accellion FTA 9_12_370 and earlier is affected by OS command execution via a crafted POST request to various admin endpoints.
Affected: Fta (Accellion). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 13, 2021 and is known to be used in ransomware campaigns.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including Fta <=9_12_370, Fta 9_12_370.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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