CVE-2021-4315Public exploitNetwork attack vector

Authenticated code execution via mode template injection

Published Jan 28, 2023 · Updated Aug 3, 2024

Server-side template injection in psiTurk before 3.2.1 allows remote authenticated users to execute arbitrary Python code via the mode parameter. The advertisement and consent handlers concatenate the HTTP mode value into template text before passing it to Flask's render_template_string. A low-privileged network user can read server-side files and execute code in the experiment server process.

CVSS severity8.7
High
EPSS probability0.91%
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 psiTurk before 3.2.1 allows remote authenticated users to execute arbitrary Python code via the mode parameter. The advertisement and consent handlers concatenate the HTTP mode value into template text before passing it to Flask's render_template_string. A low-privileged network user can read server-side files and execute code in the experiment server process.

The record

CVE
CVE-2021-4315
Published
Jan 28, 2023
Updated
Aug 3, 2024
Vendor
NYU Computation and Cognition Lab
Product
psiTurk
Classifications
CWE-1336, CWE-94, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 28, 2023CVE 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.0
  2. Affected versionversion=3.1
  3. Affected versionversion=3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

NYU Computation and Cognition Lab · psiTurkversion=3.0; version=3.1; version=3.2

Published CVSS scores

8.7GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
5.2VulDBAV:A/AC:L/Au:S/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5VulDBCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:L/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 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-1336Improper Neutralization of Special Elements Used in a Template Engine
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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