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CVE Record

CVE-2021-4263: leanote history.js define cross site scripting

A vulnerability, which was classified as problematic, has been found in leanote 2.6.1. This issue affects the function define of the file public/js/plugins/history.js. The manipulation of the argument content leads to cross site scripting. The attack may be initiated remotely. The identifier of the patch is 0f9733c890077942150696dcc6d2b1482b7a0a19. It is recommended to apply a patch to fix this issue. The identifier VDB-216461 was assigned to this vulnerability.

MediumCVSS 4Not KEV-listedUpdated
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Glexia's Takemoderate

Analyst readout for executives and security teams

Plain-English summary

Leanote 2.6.1 contains a cross-site scripting flaw in a JavaScript history plugin. A remote authenticated attacker could manipulate content handled by the affected function and cause script execution in a user's browser. The cited sources rate it medium/problematic, with integrity impact and no stated confidentiality or availability impact.

Executive priority

Treat this as a moderate web application risk. It is not described as actively exploited, but XSS can affect user trust and data integrity in browser sessions. Patch confirmed Leanote 2.6.1 deployments during normal remediation cycles, sooner for externally reachable services.

Technical view

CVE-2021-4263 is CWE-79 in public/js/plugins/history.js, affecting the define function and its content argument in Leanote 2.6.1. The supplied CVSS v2 vector is AV:N/AC:L/Au:S/C:N/I:P/A:N, score 4.0. The source identifies patch commit 0f9733c890077942150696dcc6d2b1482b7a0a19.

Likely exposure

Exposure is limited to organizations running Leanote 2.6.1, especially reachable self-hosted instances with authenticated users. The source bundle does not identify other affected versions or products.

Exploitation context

The attack may be initiated remotely, but the CVSS vector indicates authentication is required. The source bundle does not show CISA KEV listing or any cited evidence of active exploitation.

Researcher notes

Evidence is narrow: Leanote 2.6.1, history.js define, content argument, CWE-79, and one patch commit. Do not assume broader version impact, exploit availability, or compensating controls without additional vendor evidence.

Mitigation direction

  • Identify any Leanote 2.6.1 deployments.
  • Apply the patch identified by commit 0f9733c890077942150696dcc6d2b1482b7a0a19.
  • Check Leanote project guidance for any fixed release packaging.
  • Track CVE-2021-4263 until patch status is confirmed.

Validation and detection

  • Inventory Leanote instances and record exact versions.
  • Confirm whether public/js/plugins/history.js includes the cited patch.
  • Review vulnerability scanner results for CVE-2021-4263 or VDB-216461.
  • Verify exposed instances require intended authentication controls.
Prepared
Confidence
high
Sources
5

Public sources used

Based on public source material and reviewed before publication.

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-79: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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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cve · low confidence lookup

CVE-2021-4263 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4 (2.0)
Known Exploited
No
Published

Vector: AV:N/AC:L/Au:S/C:N/I:P/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
4Source 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
4CVSS 2.0MediumAV:N/AC:L/Au:S/C:N/I:P/A:N82.9Primary CVE score

Vulnerability scoring details

Base CVSS 2.0 score

4Medium
CVSS 2.0 vector shape for CVE-2021-4263Access VectorAccess ComplexityAuthenticationConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: AV:N/AC:L/Au:S/C:N/I:P/A:N

Access Vector
NetworkAdjacentLocal
Access Complexity
LowMediumHigh
Authentication
NoneSingleMultiple
Confidentiality Impact
CompletePartialNone
Integrity Impact
CompletePartialNone
Availability Impact
CompletePartialNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aleanote2.6.1Listed
Weakness

CWE details

CWE-79

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

CWE-79 · source CWE mapping

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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