CVE-2021-20473Network attack vector

User impersonation via persistent post-logout sessions

Published Oct 7, 2021 · Updated Sep 16, 2024

Session expiration failure in affected IBM Sterling File Gateway releases allows remote authenticated users to impersonate other users. The web user interface leaves an authenticated session valid after logout instead of invalidating its server-side session state. Authentication is required; affected ranges are 2.2.0.0 through 5.2.6.5_3, 6.0.0.0 through 6.0.3.4, and 6.1.0.0 through 6.1.0.1.

CVSS severity6.3
Medium
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session expiration failure in affected IBM Sterling File Gateway releases allows remote authenticated users to impersonate other users. The web user interface leaves an authenticated session valid after logout instead of invalidating its server-side session state. Authentication is required; affected ranges are 2.2.0.0 through 5.2.6.5_3, 6.0.0.0 through 6.0.3.4, and 6.1.0.0 through 6.1.0.1.

The record

CVE
CVE-2021-20473
Published
Oct 7, 2021
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM Sterling File Gateway
Classifications
CWE-613, T1550.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.2.0.0
  2. Affected versionversion=5.2.6.5_3
  3. Affected versionversion=6.0.0.0
  4. Affected versionversion=6.0.3.4
  5. Affected versionversion=6.1.0.0
  6. Affected versionversion=6.1.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

IBM · IBM Sterling File Gatewayversion=2.2.0.0; version=5.2.6.5_3; version=6.0.0.0; version=6.0.3.4; version=6.1.0.0; version=6.1.0.1

Published CVSS scores

6.3IBM CorporationCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-613Insufficient Session Expiration
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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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