CVE-2021-39906Public exploitNetwork attack vector

Account takeover via notebook SVG path traversal

Published Nov 4, 2021 · Updated Aug 4, 2024

Stored XSS in GitLab CE/EE 13.5 through 14.2.5, 14.3 through 14.3.3, and 14.4.0 allows remote authenticated users to execute JavaScript. The notebook blob viewer permits SVG use elements, and its DOMPurify URL check accepts an allowed icon-path prefix followed by traversal to an attacker-controlled SVG. A victim using Firefox need only view the crafted notebook; the script runs as that authenticated user and can expose data or perform account actions.

CVSS severity8.7
High
EPSS probability60.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in GitLab CE/EE 13.5 through 14.2.5, 14.3 through 14.3.3, and 14.4.0 allows remote authenticated users to execute JavaScript. The notebook blob viewer permits SVG use elements, and its DOMPurify URL check accepts an allowed icon-path prefix followed by traversal to an attacker-controlled SVG. A victim using Firefox need only view the crafted notebook; the script runs as that authenticated user and can expose data or perform account actions.

The record

CVE
CVE-2021-39906
Published
Nov 4, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 4, 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=>=13.5, <14.2.6
  2. Affected versionversion=>=14.3, <14.3.4
  3. Affected versionversion=>=14.4, <14.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=>=13.5, <14.2.6; version=>=14.3, <14.3.4; version=>=14.4, <14.4.1

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
8.7GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo