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CVE Record

CVE-2021-23562: Arbitrary File Upload

This affects the package plupload before 2.3.9. A file name containing JavaScript code could be uploaded and run. An attacker would need to trick a user to upload this kind of file.

MediumCVSS 4.2Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-23562 affects plupload before 2.3.9. A crafted filename containing JavaScript could be uploaded and later run. The attack requires user interaction, so business urgency is moderate, focused on applications that expose plupload upload widgets to customers, staff, or partners.

Executive priority

Treat as a planned remediation item unless plupload is used in externally exposed or high-volume upload workflows. Prioritize upgrades where customers or partners upload files through vulnerable interfaces.

Technical view

The vulnerability is an arbitrary file upload issue in plupload before 2.3.9 involving unsafe handling of uploaded filenames containing JavaScript. CVSS 3.1 is 4.2 with network attack vector, high complexity, no privileges, and required user interaction. Sources do not assign a CWE.

Likely exposure

Exposure is most likely where plupload, or WebJars packaging of plupload, is embedded in web applications that accept user-selected uploads and display uploaded filenames back in the browser.

Exploitation context

The provided sources and KEV flag do not show active exploitation. Exploitation requires tricking a user into uploading a specially named file, limiting automated abuse but still creating risk in shared upload workflows.

Researcher notes

Focus validation on filename rendering behavior and bundled copies of plupload. The source bundle identifies multiple Snyk package records and an upstream commit, but does not provide evidence of exploitation in the wild.

Mitigation direction

  • Upgrade plupload to 2.3.9 or later.
  • Update affected WebJars packages that bundle vulnerable plupload versions.
  • Check vendor and package guidance before applying compensating controls.
  • Sanitize and encode displayed filenames in upload interfaces.
  • Restrict risky upload flows where vulnerable versions cannot be upgraded promptly.

Validation and detection

  • Inventory direct and transitive plupload dependencies.
  • Check package-lock, yarn.lock, pnpm-lock, Maven, and WebJars references.
  • Confirm deployed assets are not serving plupload before 2.3.9.
  • Review upload UI paths that display filenames after selection or upload.
  • Run dependency scanning against JavaScript and Java package manifests.
Prepared
Confidence
high
Sources
7

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.

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-2021-23562 mapping review

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

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.2 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
0Timeline events
0ADP providers
7Source links

CVSS vector scores

1 official score

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
4.2CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N1.62.5Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

4.2Medium
CVSS 3.1 vector shape for CVE-2021-23562Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/apluploadunspecifiedListed
Weakness

CWE details

No CWE listed

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