CVE-2021-39896Network attack vector

Account misattribution via incorrect impersonation-session restoration

Published Oct 4, 2021 · Updated Aug 4, 2024

Improper access control in affected GitLab CE/EE releases since 8.0 allows administrators to remain signed in as an impersonated user. After an administrator impersonates two users in sequence and stops impersonating, the session restores the second impersonated user instead of the administrator; GitLab has not published the responsible function. Administrator privileges and two consecutive impersonations are required, and later activity can be attributed to the wrong account while using that account's access.

CVSS severity3.8
Low
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in affected GitLab CE/EE releases since 8.0 allows administrators to remain signed in as an impersonated user. After an administrator impersonates two users in sequence and stops impersonating, the session restores the second impersonated user instead of the administrator; GitLab has not published the responsible function. Administrator privileges and two consecutive impersonations are required, and later activity can be attributed to the wrong account while using that account's access.

The record

CVE
CVE-2021-39896
Published
Oct 4, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
Unavailable
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Oct 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=>=14.2, <14.2.5
  2. Affected versionversion=>=14.3, <14.3.1
  3. Affected versionversion=>=8.0, <14.1.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

GitLab · GitLabversion=>=14.2, <14.2.5; version=>=14.3, <14.3.1; version=>=8.0, <14.1.7

Published CVSS scores

3.8GitLabCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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