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NVD / CVE Program· CNA mitre

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…

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Plan (action score 40/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 4.7% (FIRST EPSS); higher than 92% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: showdoc/showdoc (Packagist) 2.9.6.

Add it to your regular patch cycle. Upgrade to showdoc/showdoc (Packagist) 2.9.6 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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'.

Published
Sep 8, 2021
Updated
Jun 16, 2026
EPSS
4.7% · 92th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.7%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
showdocshowdoc

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • showdoc showdoc2.9.5

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Packagistshowdoc/showdocbefore 2.9.62.9.6

Same product

showdoc: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-0362SQL Injection in star7th/showdoc
    39Monitor
  • CVE-2021-41745ShowDoc 2.8.3 ihas a file upload vulnerability, where attackers can use the vulnerability to obtain server permissions.
    39Monitor
  • CVE-2025-0520ShowDoc < 2.8.7 Unauthenticated File Upload Remote Code Execution
    38Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-3680Aug 4, 2021 · Missing Cryptographic Step in star7th/showdoc
    19Monitor
  • ← EarlierCVE-2021-3678Aug 4, 2021 · Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in star7th/showdoc
    23Monitor
  • Later →CVE-2021-3683Nov 13, 2021 · Cross-Site Request Forgery (CSRF) in star7th/showdoc
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Packagist:showdoc/showdoc2.9.6Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-434 · Unrestricted Upload of File with Dangerous Type

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

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