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CVE Record

CVE-2021-47943: TextPattern CMS 4.8.7 Remote Code Execution via File Upload

TextPattern CMS 4.8.7 contains a remote code execution vulnerability that allows authenticated attackers to execute arbitrary commands by uploading malicious PHP files through the file upload functionality. Attackers can upload a PHP shell via the Files section in the content area and execute commands by accessing the uploaded file at /textpattern/files/ with GET parameters passed to the system function.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A flaw in TextPattern CMS version 4.8.7 lets a logged-in user upload a malicious PHP file through the built-in Files section and then run commands on the web server. In plain terms, anyone with publishing access can take over the site and the host it runs on.

Executive priority

Treat as a high-priority patch or compensating-control action for any production TextPattern 4.8.7 site, especially public-facing. Risk is full site and server compromise once any author-level credential is obtained, with public exploit code already circulating.

Technical view

CWE-434 unrestricted file upload in TextPattern CMS 4.8.7. An authenticated user uploads a PHP payload via the content area Files feature; the file is served from /textpattern/files/ and executes server-side, enabling arbitrary command execution. CVSS 3.1 base 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) reflects low-privilege network-reachable RCE.

Likely exposure

Internet-exposed TextPattern 4.8.7 installations where authors, editors, or compromised low-privilege accounts can reach the file upload feature. Sites with weak credentials, open registration, or shared author accounts face the broadest exposure; intranet deployments are reachable to any insider with a valid login.

Exploitation context

Two public proof-of-concept entries exist on ExploitDB (49996 and 50415) and a VulnCheck advisory documents the issue. CISA KEV does not list active exploitation. Working exploit code being public lowers the skill barrier and raises the chance of opportunistic abuse against any unpatched, authenticated-accessible installation.

Researcher notes

CWE-434 with a documented path: upload via Files, retrieve via /textpattern/files/, command passed as GET parameter to a system call. Sources do not name a fixed release in this bundle, so consult Textpattern's release notes and GitHub repository directly. KEV flag is false; treat exploitation as plausible given public PoCs but not confirmed in-the-wild.

Mitigation direction

  • Inventory all TextPattern CMS instances and confirm whether any are running 4.8.7.
  • Check Textpattern vendor advisories and release notes for a fixed version and upgrade.
  • Restrict the Files upload feature to trusted admin roles and remove unused author accounts.
  • Block or rename /textpattern/files/ at the web server or WAF, and disable PHP execution in upload directories.
  • Enforce strong authentication and MFA on all CMS accounts; rotate credentials on suspected sites.
  • Monitor web server logs for unexpected PHP files served from the files directory.

Validation and detection

  • Confirm CMS version by reviewing Admin > Diagnostics or the textpattern/lib version constants.
  • Review the files directory and database for PHP-extension uploads that should not be present.
  • Audit user accounts and recent login activity for unknown or dormant privileged users.
  • Search web and application logs for GET requests to /textpattern/files/ with query parameters.
  • After remediation, retest by attempting a benign non-PHP upload to verify allow-list controls.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-434: File access and web shell behavior lookup

File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-47943 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
3Timeline events
1ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9VulnCheck
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——VulnCheck

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2021-47943Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
TextpatternTextPattern CMS4.8.7Listed
Weakness

CWE details

CWE-434

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.