CVE-2021-36440Public exploitNetwork attack vector

Unauthenticated code execution via attacker-supplied update archive

Published Sep 8, 2021 · Updated Aug 4, 2024

Unrestricted file upload in ShowDoc 2.9.5 allows remote attackers to execute arbitrary code via a crafted file_url request. AdminUpdateController downloads the supplied URL as an archive, extracts it, and copies package contents into the web-accessible update directory. No authentication or user interaction is required, and attacker-controlled files placed under the web root enable server-side code execution.

CVSS severity9.8
Critical
EPSS probability4.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in ShowDoc 2.9.5 allows remote attackers to execute arbitrary code via a crafted file_url request. AdminUpdateController downloads the supplied URL as an archive, extracts it, and copies package contents into the web-accessible update directory. No authentication or user interaction is required, and attacker-controlled files placed under the web root enable server-side code execution.

The record

CVE
CVE-2021-36440
Published
Sep 8, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1105
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 2021CVE 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

7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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-434Unrestricted Upload of File with Dangerous Type
T1105Ingress Tool Transfer

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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