CVE-2021-20376Network attack vector

Authenticated username enumeration via response discrepancies

Published Oct 7, 2021 · Updated Sep 17, 2024

Information disclosure in IBM Sterling File Gateway affected releases allows remote authenticated users to enumerate valid usernames. The user interface returns observably different messages for supplied usernames instead of an indistinguishable response for valid and invalid accounts. A valid account is required to reach the behavior, and the disclosed information is limited to determining which usernames exist.

CVSS severity4.3
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in IBM Sterling File Gateway affected releases allows remote authenticated users to enumerate valid usernames. The user interface returns observably different messages for supplied usernames instead of an indistinguishable response for valid and invalid accounts. A valid account is required to reach the behavior, and the disclosed information is limited to determining which usernames exist.

The record

CVE
CVE-2021-20376
Published
Oct 7, 2021
Updated
Sep 17, 2024
Vendor
IBM
Product
IBM Sterling File Gateway
Classifications
CWE-203, T1087
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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

4.3IBM CorporationCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-203Observable Discrepancy
T1087Account Discovery

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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