CVE-2023-1555Network attack vector

Namespace API access via unenforced user ban

Published Sep 1, 2023 · Updated Nov 20, 2025

Improper access control in affected GitLab releases allows remote authenticated users banned from a namespace to access its API. The API authorization path continues processing requests from accounts marked banned at the namespace level instead of denying them. Exploitation requires valid credentials for such an account; GitLab has not identified the affected endpoints or reported broader access.

CVSS severity4.3
Medium
EPSS probability0.46%
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 releases allows remote authenticated users banned from a namespace to access its API. The API authorization path continues processing requests from accounts marked banned at the namespace level instead of denying them. Exploitation requires valid credentials for such an account; GitLab has not identified the affected endpoints or reported broader access.

The record

CVE
CVE-2023-1555
Published
Sep 1, 2023
Updated
Nov 20, 2025
Vendor
GitLab
Product
GitLab
Classifications
CWE-262, T1078
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 1, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 20, 2025Record 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=15.2 <16.1.5
  2. Affected versionversion=16.2 <16.2.5
  3. Affected versionversion=16.3 <16.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=15.2 <16.1.5; version=16.2 <16.2.5; version=16.3 <16.3.1

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-262Not Using Password Aging
T1078Valid Accounts

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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