CVE-2021-39946Public exploitNetwork attack vector

Stored XSS via unescaped emoji markup

Published Jan 18, 2022 · Updated Aug 4, 2024

Stored XSS in affected GitLab CE/EE 14.3–14.5 releases lets remote authenticated users run script when another user views a crafted note. SyntaxHighlightFilter interpolates an unescaped data-sourcepos attribute into HTML, while gl-emoji places an unescaped name into image markup. Comment access is required, and execution occurs only when another user opens the poisoned issue, snippet, or other page containing the note.

CVSS severity8.7
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in affected GitLab CE/EE 14.3–14.5 releases lets remote authenticated users run script when another user views a crafted note. SyntaxHighlightFilter interpolates an unescaped data-sourcepos attribute into HTML, while gl-emoji places an unescaped name into image markup. Comment access is required, and execution occurs only when another user opens the poisoned issue, snippet, or other page containing the note.

The record

CVE
CVE-2021-39946
Published
Jan 18, 2022
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 18, 2022CVE 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=>=14.3, <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=>=14.3, <14.3.6; version=>=14.4, <14.4.4; version=>=14.5, <14.5.2

Published CVSS scores

8.7GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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')
T1203Exploitation for Client Execution

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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