Security Resilience

CVE-2021-30533

Access Control in Fedoraproject Fedora 33 … 34

CISA KEVActive ExploitationEUVD ExploitedPublic PoCAccess Control
Published
07 June 2021
Modified
24 October 2025
KEV Added
27 June 2022
Patch / advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
EPSS Score 0.17 97th percentile
Risk Priority 76 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2021-30533 is a medium-severity Incorrect Authorization (CWE-863) vulnerability in Fedoraproject Fedora. Its CVSS base score is 6.5 (Medium).

Operationally, ranked in the top 3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

The vulnerability is insufficient policy enforcement in the PopupBlocker component of Google Chrome versions prior to 91.0.4472.77. It is tracked as CVE-2021-30533 with CWE-863 and carries a CVSS 3.1 score of 6.5. The flaw permits bypass of navigation restrictions when a crafted iframe is rendered.

A remote attacker can exploit the issue by serving malicious web content that loads the iframe in a victim's browser. Successful exploitation requires user interaction but allows the attacker to circumvent intended navigation controls, resulting in unauthorized integrity changes without affecting confidentiality or availability.

Chrome release notes and downstream advisories for Fedora and Gentoo indicate that the issue is resolved by updating to Chrome 91.0.4472.77 or later, with corresponding package updates published for affected Linux distributions. No information on in-the-wild exploitation is provided in the references.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Insufficient policy enforcement in PopupBlocker in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass navigation restrictions via a crafted iframe.

CWE(s)
KEV Date Added
27 June 2022

Related Threats

CVEs Like This One

CVE-2021-30554Same product: Fedoraproject Fedoraboth on KEV
CVE-2024-5274Same product: Fedoraproject Fedoraboth on KEV
CVE-2024-4947Same product: Fedoraproject Fedoraboth on KEV
CVE-2021-21220Same product: Fedoraproject Fedoraboth on KEV
CVE-2024-4671Same product: Fedoraproject Fedoraboth on KEV
CVE-2022-3075Same product: Fedoraproject Fedoraboth on KEV
CVE-2021-30551Same product: Fedoraproject Fedoraboth on KEV
CVE-2022-3038Same product: Fedoraproject Fedoraboth on KEV
CVE-2024-4761Same product: Fedoraproject Fedoraboth on KEV
CVE-2021-30632Same product: Fedoraproject Fedoraboth on KEV

Affected Assets

google
chrome
≤ 91.0.4472.77
fedoraproject
fedora
33, 34

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-863

Periodic review and update of procedures reduces incorrect authorization implementations over time.

addresses: CWE-863

Supervision identifies cases where authorization logic incorrectly permits unauthorized actions.

addresses: CWE-863

Defining permitted attribute values and auditing modifications reduces the chance of incorrect authorization outcomes due to tampered or missing labels.

addresses: CWE-863

The authorization process and usage restrictions help prevent incorrect authorization for remote access types.

addresses: CWE-863

Establishing configuration and connection requirements helps ensure correct rather than incorrect authorization for wireless access.

addresses: CWE-863

Establishing connection authorization processes for mobile devices helps ensure authorization decisions are correctly implemented rather than incorrect.

addresses: CWE-863

Monitoring account use, notifying on changes, and reviewing accounts for compliance corrects incorrect authorization assignments.

addresses: CWE-863

Ensures authorization decisions for external system use are correctly implemented and enforced.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

blocks

Requiring consistency between access rights and classification plus formal approval steps ensures that the authorization logic correctly distinguishes between entities that should and should not be granted access.

blocks

A.5.18's provisioning, revocation, review and adjustment of access rights (incl. before role changes/termination, with segregation and owner approval) directly stops incorrect authorization decisions from being exploitable in the vast majority of cases; the bounded remainder is incorrectness inside the authorization logic itself (e.g. flawed conditional or missing check) rather than rights that were wrongly granted.

blocks

A.8.3 directly mandates restricting access to information per policies via configuration, identity/group controls, isolation, and dynamic techniques that enforce correct authorization decisions, addressing most but not all slices of CWE-863 (e.g., remainder in non-access-decision authorization errors like timing or environmental factors).

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-863, a class-level weakness, and none of its children carries one either.

References