CVE-2021-3183Public exploitNetwork attack vector

Cloud storage access via persistent logout session

Published Jan 19, 2021 · Updated Aug 3, 2024

Authentication bypass in Files.com Fat Client 3.3.6 allows attackers with local drive access to retain cloud storage access after logout. The client leaves an authenticated session usable after logout even when its login profile is removed. Exploitation requires access to the victim’s C drive and grants access to that victim’s stored files, with no reported write or availability impact.

CVSS severity7.5
High
EPSS probability1.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Files.com Fat Client 3.3.6 allows attackers with local drive access to retain cloud storage access after logout. The client leaves an authenticated session usable after logout even when its login profile is removed. Exploitation requires access to the victim’s C drive and grants access to that victim’s stored files, with no reported write or availability impact.

The record

CVE
CVE-2021-3183
Published
Jan 19, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-613
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-613Insufficient Session Expiration

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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