CVE-2021-3994Network attack vector

Stored script execution via flawed Markdown link filtering

Published Dec 1, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in django-helpdesk before 0.3.2 allows remote attackers to execute script through crafted Markdown links. The get_markdown function applies a flawed regular expression when checking URL schemes, then passes the rendered Markdown to mark_safe. Execution occurs when another user views the stored ticket text, allowing the script to act in that user's browser session.

CVSS severity9.6
Critical
EPSS probability1.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in django-helpdesk before 0.3.2 allows remote attackers to execute script through crafted Markdown links. The get_markdown function applies a flawed regular expression when checking URL schemes, then passes the rendered Markdown to mark_safe. Execution occurs when another user views the stored ticket text, allowing the script to act in that user's browser session.

The record

CVE
CVE-2021-3994
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
django-helpdesk
Product
django-helpdesk
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 1, 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?

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

  1. Affected versionversion=unspecified <0.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

django-helpdesk · django-helpdeskversion=unspecified <0.3.2

Published CVSS scores

9.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
8.8huntr.devCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
6.8NIST NVDAV:N/AC:M/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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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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