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No exploitation reportedFix available

CVE-2021-36440

No exploitation reported by the sources we read.

  • Published2021-09-08
  • Fixed in2.9.6
  • WeaknessCWE-434

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Unrestricted File Upload in ShowDoc v2.9.5 allows remote attackers to execute arbitrary code via the 'file_url' parameter in the component AdminUpdateController.class.php'.

Timeline

dates in UTC
  1. 2021-09-0821:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-36440?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-36440?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD
showdoc/showdoc
BranchAffectedFixed in
2.9< 2.9.62.9.6
Showdoc
BranchAffectedFixed in
2.9= 2.9.5no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update showdoc/showdoc to 2.9.6

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • NVDweakness (CWE)CWE-434read 2026-10-23
  • FIRST EPSSEPSS score4.8 %2026-11-03
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryCRITICAL2021-09-09

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-09-08
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-c442-3278-rhrg

Frequently asked questions

What is CVE-2021-36440?

Unrestricted File Upload in ShowDoc v2.9.5 allows remote attackers to execute arbitrary code via the 'file_url' parameter in the component AdminUpdateController.class.php'.

Is CVE-2021-36440 actively exploited?

Active exploitation of CVE-2021-36440 has not been confirmed. Its EPSS score was 4.8% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-36440?

CVE-2021-36440 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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