CVE-2023-3909Network attack vector

Service interruption via oversized CI timeout value

Published Nov 6, 2023 · Updated Nov 20, 2025

Regular expression denial of service in GitLab CE/EE allows remote authenticated users to interrupt service through crafted CI configuration. The timeout parser applies an inefficient regular expression to an attacker-controlled timeout value in gitlab-ci.yml, so a sufficiently long string consumes excessive processing time. Project access permitting CI configuration changes is required; affected versions are 12.3 through 16.3.5, 16.4.0 through 16.4.1, and 16.5.0.

CVSS severity4.3
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in GitLab CE/EE allows remote authenticated users to interrupt service through crafted CI configuration. The timeout parser applies an inefficient regular expression to an attacker-controlled timeout value in gitlab-ci.yml, so a sufficiently long string consumes excessive processing time. Project access permitting CI configuration changes is required; affected versions are 12.3 through 16.3.5, 16.4.0 through 16.4.1, and 16.5.0.

The record

CVE
CVE-2023-3909
Published
Nov 6, 2023
Updated
Nov 20, 2025
Vendor
GitLab
Product
GitLab
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 6, 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=12.3 <16.3.6
  2. Affected versionversion=16.4 <16.4.2
  3. Affected versionversion=16.5 <16.5.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=12.3 <16.3.6; version=16.4 <16.4.2; version=16.5 <16.5.1

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.3GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.004Application or System Exploitation

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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