CVE-2021-39891Network attack vector

Sensitive data disclosure via uncleared impersonation tokens

Published Oct 5, 2021 · Updated Aug 4, 2024

Improper access control in GitLab allows remote authenticated users to retain access tokens after administrator impersonation ends. The impersonation session lifecycle leaves session access tokens uncleared when impersonation starts or stops, allowing token-backed access to outlive the session. Administrator access and enabled impersonation are required; retained tokens expose user-scoped information and authorize actions within their scopes.

CVSS severity5.9
Medium
EPSS probability1.00%
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 GitLab allows remote authenticated users to retain access tokens after administrator impersonation ends. The impersonation session lifecycle leaves session access tokens uncleared when impersonation starts or stops, allowing token-backed access to outlive the session. Administrator access and enabled impersonation are required; retained tokens expose user-scoped information and authorize actions within their scopes.

The record

CVE
CVE-2021-39891
Published
Oct 5, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-212, T1550.001
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Oct 5, 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

4.9NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
5.9GitLab Inc.CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/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.

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

CWE-212Improper Removal of Sensitive Information Before Storage or Transfer
T1550.001Use Alternate Authentication Material: Application Access Token

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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