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CVE Record

CVE-2021-36830: WordPress Comment Guestbook plugin <= 0.8.0 - Authenticated Stored Cross-Site Scripting (XSS) vulnerability

Authenticated (admin+) Stored Cross-Site Scripting (XSS) vulnerability in Comment Guestbook plugin <= 0.8.0 at WordPress.

MediumCVSS 4.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

A logged-in WordPress administrator could store script content through the Comment Guestbook plugin, and another user could later trigger it by viewing affected content. The risk is limited by the need for admin-level access, but it can still affect site integrity and user trust.

Executive priority

Treat this as a moderate hygiene issue. It is not reported as actively exploited in the provided sources, but vulnerable public WordPress sites should be inventoried and remediated because compromised administrator accounts could turn this into a user-facing trust issue.

Technical view

CVE-2021-36830 is a CWE-79 stored XSS issue in mibuthu Comment Guestbook for WordPress versions <= 0.8.0. The CVSS vector requires network access, low attack complexity, high privileges, user interaction, changed scope, low confidentiality and integrity impact, and no availability impact.

Likely exposure

Exposure is limited to WordPress sites with the Comment Guestbook plugin installed at version 0.8.0 or earlier. The source bundle does not identify affected hosted services, themes, or other plugins.

Exploitation context

The source bundle does not show KEV listing or cited evidence of active exploitation. Exploitation requires an authenticated administrator-level user and user interaction, reducing broad opportunistic risk but not eliminating insider, compromised-admin, or supply-chain account scenarios.

Researcher notes

Evidence is narrow: the bundle identifies the affected plugin, version range, CWE, CVSS vector, and references, but does not provide patch details or exploitation telemetry. Avoid assuming unauthenticated impact, broad WordPress core exposure, or a specific fixed version without vendor confirmation.

Mitigation direction

  • Inventory WordPress sites for Comment Guestbook version 0.8.0 or earlier.
  • Check WordPress.org and vendor guidance for a fixed or safe plugin version.
  • Disable or remove the plugin where no safe version is confirmed.
  • Limit administrator access to trusted accounts with MFA and least privilege.
  • Review recent administrator activity for unexpected guestbook or comment content.

Validation and detection

  • Confirm whether the Comment Guestbook plugin is installed on each WordPress site.
  • Record the installed plugin version and compare it to <= 0.8.0.
  • Review administrator accounts for compromise, stale access, or excessive privileges.
  • Inspect relevant guestbook/comment content for unexpected embedded script-like markup.
  • Verify any remediation by rechecking plugin presence and version after change control.
Prepared
Confidence
high
Sources
4

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-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-2021-36830 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
Medium
CVSS
4.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/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
3Source 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
4.8CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N1.72.7Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

4.8Medium
CVSS 3.1 vector shape for CVE-2021-36830Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/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
mibuthuComment Guestbook (WordPress plugin)<= 0.8.0Listed
Weakness

CWE details

CWE-79

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