CVE-2021-25770Public exploitNetwork attack vector

Code execution via notification template sandbox escape

Published Feb 3, 2021 · Updated Aug 3, 2024

Server-side template injection in JetBrains YouTrack before 2020.5.3123 allows attackers to execute code through notification previews. The preview API renders attacker-controlled FreeMarker content, and FreeMarker 2.3.23 permits a reflection-based sandbox escape through ObjectWrapper.DEFAULT_WRAPPER. The demonstrated exploit uses an authenticated administrative request, although the published CVSS assessment lists no privileges required.

CVSS severity9.8
Critical
EPSS probability3.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side template injection in JetBrains YouTrack before 2020.5.3123 allows attackers to execute code through notification previews. The preview API renders attacker-controlled FreeMarker content, and FreeMarker 2.3.23 permits a reflection-based sandbox escape through ObjectWrapper.DEFAULT_WRAPPER. The demonstrated exploit uses an authenticated administrative request, although the published CVSS assessment lists no privileges required.

The record

CVE
CVE-2021-25770
Published
Feb 3, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1190Exploit Public-Facing Application

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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