CVE-2021-46703Public exploitNetwork attack vector

Sandbox escape via compiled Razor expressions

Published Mar 6, 2022 · Updated Aug 4, 2024

Code injection in Antaris RazorEngine through 4.5.1-alpha001 allows attackers to execute arbitrary .NET code through crafted templates. IsolatedRazorEngineService compiles externally controlled Razor expressions under CAS isolation, while RazorDynamicObject permits a file-writing delegate to be compiled and run. Exploitation requires CAS-backed isolation and external control of template contents; the resulting code escapes the intended sandbox and can access host resources.

CVSS severity9.8
Critical
EPSS probability1.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Antaris RazorEngine through 4.5.1-alpha001 allows attackers to execute arbitrary .NET code through crafted templates. IsolatedRazorEngineService compiles externally controlled Razor expressions under CAS isolation, while RazorDynamicObject permits a file-writing delegate to be compiled and run. Exploitation requires CAS-backed isolation and external control of template contents; the resulting code escapes the intended sandbox and can access host resources.

The record

CVE
CVE-2021-46703
Published
Mar 6, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1336, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 6, 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

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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

9.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NISTAV: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-1336Improper Neutralization of Special Elements Used in a Template Engine
T1059Command and Scripting Interpreter

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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