CVE-2021-39940Public exploitNetwork attack vector

CPU exhaustion via Maven version regex backtracking

Published Dec 13, 2021 · Updated Aug 4, 2024

Regular expression denial of service in affected GitLab CE/EE releases allows remote authenticated users to exhaust server CPU. The Maven Package Registry version validator applies a backtracking-prone regular expression to a crafted package version string. A user able to publish a Maven package can consume request-processing CPU and interrupt registry service.

CVSS severity4.3
Medium
EPSS probability1.46%
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 affected GitLab CE/EE releases allows remote authenticated users to exhaust server CPU. The Maven Package Registry version validator applies a backtracking-prone regular expression to a crafted package version string. A user able to publish a Maven package can consume request-processing CPU and interrupt registry service.

The record

CVE
CVE-2021-39940
Published
Dec 13, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 13, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>=13.2, <14.3.6
  2. Affected versionversion=>=14.4, <14.4.4
  3. Affected versionversion=>=14.5, <14.5.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=>=13.2, <14.3.6; version=>=14.4, <14.4.4; version=>=14.5, <14.5.2

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
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P

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-1333Inefficient Regular Expression Complexity
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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