CVE-2021-21166
Race Condition in Fedoraproject Fedora 32 … 34
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2021-21166 is a high-severity Race Condition (CWE-362) vulnerability in Fedoraproject Fedora. Its CVSS base score is 8.8 (High).
Operationally, ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
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 a data race in the audio component of Google Chrome, tracked as CWE-362, that affects all versions prior to 89.0.4389.72. The flaw can result in heap corruption when processing certain inputs.
A remote attacker can exploit the issue by convincing a user to visit a crafted HTML page. Successful exploitation may allow the attacker to achieve heap corruption with high impact on confidentiality, integrity, and availability, as reflected in the CVSS 8.8 score requiring only user interaction and no other privileges.
The referenced Chrome stable channel update and Fedora package advisories indicate that the issue is resolved by upgrading to Chrome 89.0.4389.72 or later, with corresponding updates distributed through standard package channels for affected Linux distributions. No information on observed in-the-wild exploitation is provided in the references.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-8557
Vulnerability Data
Data race in audio in Google Chrome prior to 89.0.4389.72 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
- CWE(s)
- KEV Date Added
- 03 November 2021
Related Threats
CVEs Like This One
Affected Assets
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.
Accurate timestamps from internal clocks enable detection of race conditions by providing reliable event ordering in audit logs.
Coordination of concurrent security activities reduces the probability that shared resources will be accessed simultaneously without proper synchronization.
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.
A.8.25 mandates secure SDLC practices (secure coding guidelines, security requirements, checkpoints, testing including code scans/penetration tests, developer training) that reach race conditions in concurrent code, but only as one slice of a broad requirement whose implementation scope and rigour are left to the organisation.
A.8.26 explicitly lists resilience against malicious attacks including SQL injections and input validation as application security requirements to identify/address; race conditions are a similar class of timing-based concurrency flaw that can be mitigated by requirements for proper synchronization/locking, but this is only one slice of the broad CWE-362 class (most instances arise in low-level shared-memory or TOCTOU scenarios not named here).
Secure architecture principles require proper synchronization and resource isolation, addressing the root cause of CWE-362.
Secure coding standards explicitly forbid unsafe concurrent access patterns and mandate atomic operations or locks.
Security testing can detect race conditions, but does not prevent them at design or coding time.
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-362, a class-level weakness, and none of its children carries one either.