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CVE Record

CVE-2021-30558: Insufficient policy enforcement in content security policy in Google Chrome prior to 91.0.4472.77 allowed a...

Insufficient policy enforcement in content security policy in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass content security policy via a crafted HTML page. (Chrome security severity: Medium)

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This vulnerability affected Google Chrome before 91.0.4472.77. A malicious web page could bypass Chrome's Content Security Policy enforcement, weakening a browser protection that limits what web content can load or execute. The sources do not show active exploitation, but outdated Chrome installations should be treated as meaningful endpoint risk.

Executive priority

Prioritize normal high-severity endpoint patching. The flaw can weaken browser protection when users reach malicious content, but the provided sources do not establish active exploitation or a broader platform impact.

Technical view

CVE-2021-30558 is an insufficient policy enforcement flaw in Chrome's Content Security Policy handling. A remote attacker could bypass CSP using a crafted HTML page, requiring user interaction. The source bundle lists CVSS 3.1 score 8.8, while Chrome assigned medium security severity. Fixed version indicated: Chrome 91.0.4472.77.

Likely exposure

Exposure is most likely on managed or unmanaged endpoints still running Google Chrome versions earlier than 91.0.4472.77. The source bundle does not identify affected servers, extensions, mobile builds, or Chromium-based downstream products.

Exploitation context

The CVE requires a user to open attacker-controlled HTML. CISA KEV is false in the provided bundle, and no cited source states active exploitation. Treat this as a browser hardening and patch-compliance issue, not a confirmed exploited-in-the-wild event.

Researcher notes

The public description is sparse and the Chromium bug reference may not provide full technical detail. Analysis should stay bounded to CSP policy bypass in Chrome before 91.0.4472.77, with user interaction required and no confirmed exploitation from the supplied sources.

Mitigation direction

  • Update Google Chrome to 91.0.4472.77 or newer.
  • Confirm enterprise browser auto-update is enabled and functioning.
  • Check Google Chrome release guidance for any additional vendor instructions.
  • Prioritize remediation on systems used for email, web browsing, and privileged administration.

Validation and detection

  • Inventory Chrome versions across managed endpoints.
  • Flag any Chrome build earlier than 91.0.4472.77.
  • Verify updated endpoints report the expected Chrome version after restart.
  • Review exception lists for devices blocked from browser auto-update.
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

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CVE-2021-30558 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
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

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

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
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2021-30558Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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
GoogleChromeunspecifiedListed
Weakness

CWE details

No CWE listed

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