CVE-2021-39889Public exploitNetwork attack vector

Protected branch-name disclosure via status-check IDOR

Published Oct 5, 2021 · Updated Aug 4, 2024

IDOR in GitLab EE 14.1 through 14.1.6, 14.2 through 14.2.4, and 14.3.0 allows remote authenticated users to read protected branch names. The external-status-check update endpoint accepts arbitrary protected_branch_ids and resolves them without restricting each branch to the requester's project, returning the names in its response and interface. A user with Maintainer access to another project can enumerate sequential branch IDs; the demonstrated consequence is disclosure of private protected-branch names and creation of a status check.

CVSS severity4.3
Medium
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

IDOR in GitLab EE 14.1 through 14.1.6, 14.2 through 14.2.4, and 14.3.0 allows remote authenticated users to read protected branch names. The external-status-check update endpoint accepts arbitrary protected_branch_ids and resolves them without restricting each branch to the requester's project, returning the names in its response and interface. A user with Maintainer access to another project can enumerate sequential branch IDs; the demonstrated consequence is disclosure of private protected-branch names and creation of a status check.

The record

CVE
CVE-2021-39889
Published
Oct 5, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-639
Attack vector
network
Privileges
authenticated

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=>=14.1, <14.1.7
  2. Affected versionversion=>=14.2, <14.2.5
  3. Affected versionversion=>=14.3, <14.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=>=14.1, <14.1.7; version=>=14.2, <14.2.5; version=>=14.3, <14.3.1

Published CVSS scores

4.3GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.0NIST NVDAV:N/AC:L/Au:S/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.

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 exploitPublished

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key

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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