CVE-2023-4912Public exploitNetwork attack vector

Client browser hang via unbounded Mermaid flowchart

Published Dec 1, 2023 · Updated Apr 30, 2026

Resource exhaustion in affected GitLab EE releases allows remote authenticated users to hang clients with crafted Mermaid flowcharts. The Mermaid renderer expands highly connected Flowchart TB nodes and edges without a complexity limit, driving browser CPU to 100% and delaying page loads. Exploitation requires permission to place a diagram in comment-bearing content and user interaction when a client opens or reloads that page.

CVSS severity2.6
Low
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in affected GitLab EE releases allows remote authenticated users to hang clients with crafted Mermaid flowcharts. The Mermaid renderer expands highly connected Flowchart TB nodes and edges without a complexity limit, driving browser CPU to 100% and delaying page loads. Exploitation requires permission to place a diagram in comment-bearing content and user interaction when a client opens or reloads that page.

The record

CVE
CVE-2023-4912
Published
Dec 1, 2023
Updated
Apr 30, 2026
Vendor
GitLab
Product
GitLab
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 1, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 2026Record 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=10.5 <16.4.3
  2. Affected versionversion=16.5 <16.5.3
  3. Affected versionversion=16.6 <16.6.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=10.5 <16.4.3; version=16.5 <16.5.3; version=16.6 <16.6.1

Published CVSS scores

2.6GitLab Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/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 exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
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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