CVE-2021-39938Public exploitNetwork attack vector

Service interruption via deploy command regex backtracking

Published Dec 13, 2021 · Updated Aug 4, 2024

ReDoS in GitLab CE/EE allows remote authenticated users to interrupt service through crafted deploy Slash commands. The Deploy.match regular expression in lib/gitlab/slash_commands/deploy.rb combines adjacent greedy groups, causing superlinear backtracking on newline-terminated input. A configured Slack or Mattermost slash-command integration and a valid integration token are required; CPU exhaustion degrades availability without affecting data confidentiality or integrity.

CVSS severity3.1
Low
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

ReDoS in GitLab CE/EE allows remote authenticated users to interrupt service through crafted deploy Slash commands. The Deploy.match regular expression in lib/gitlab/slash_commands/deploy.rb combines adjacent greedy groups, causing superlinear backtracking on newline-terminated input. A configured Slack or Mattermost slash-command integration and a valid integration token are required; CPU exhaustion degrades availability without affecting data confidentiality or integrity.

The record

CVE
CVE-2021-39938
Published
Dec 13, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-400, 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

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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=>=14.4, <14.4.4
  2. Affected versionversion=>=14.5, <14.5.2
  3. Affected versionversion=>=8.15, <14.3.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=>=14.4, <14.4.4; version=>=14.5, <14.5.2; version=>=8.15, <14.3.6

Published CVSS scores

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

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-400Uncontrolled Resource Consumption
T1499.004Application 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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