CVE-2021-27817Network attack vector

Unauthenticated code execution via disguised PHAR upload

Published Mar 15, 2021 · Updated Aug 3, 2024

Unrestricted file upload in ShopXO 1.9.3 allows remote attackers to execute arbitrary code by submitting a crafted PHAR file as a JPG. Public records do not identify the upload endpoint or validation function; they state only that the upload accepts a PHAR payload after its suffix is changed to JPG. No authentication or user interaction is required, and successful exploitation executes attacker-controlled code on the ShopXO server.

CVSS severity9.8
Critical
EPSS probability3.23%
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 ShopXO 1.9.3 allows remote attackers to execute arbitrary code by submitting a crafted PHAR file as a JPG. Public records do not identify the upload endpoint or validation function; they state only that the upload accepts a PHAR payload after its suffix is changed to JPG. No authentication or user interaction is required, and successful exploitation executes attacker-controlled code on the ShopXO server.

The record

CVE
CVE-2021-27817
Published
Mar 15, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 15, 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
9.8GitHub Advisory DatabaseCVSS: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application

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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