Cyber Resilience

CVE-2021-30952

Memory Safety in Fedoraproject Fedora 34 … 35

CISA KEVActive ExploitationEUVD ExploitedPublic PoCMemory Safety
Published
24 August 2021
Modified
06 March 2026
KEV Added
05 March 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.076 94th percentile
Risk Priority 83 floored blend · peak EPSS

Summary

CVE-2021-30952 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Fedoraproject Fedora. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 6% 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.

An integer overflow vulnerability, identified as CVE-2021-30952 and associated with CWE-190, was addressed via improved input validation in components handling web content. It affects multiple Apple platforms and is resolved in tvOS 15.2, macOS Monterey 12.1, Safari 15.2, iOS 15.2 and iPadOS 15.2, and watchOS 8.3. The issue carries a CVSS 3.1 score of 7.8 reflecting local attack vector, low complexity, no privileges required, and required user interaction.

An attacker can exploit the flaw by supplying maliciously crafted web content that triggers the integer overflow during processing. Successful exploitation may result in arbitrary code execution with high impact to confidentiality, integrity, and availability on the affected system.

Apple security advisories HT212975 and HT212976, along with related distribution lists, indicate that applying the listed software updates mitigates the vulnerability by incorporating the input validation fixes.

EU & UK References

Vulnerability Data

An integer overflow was addressed with improved input validation. This issue is fixed in tvOS 15.2, macOS Monterey 12.1, Safari 15.2, iOS 15.2 and iPadOS 15.2, watchOS 8.3. Processing maliciously crafted web content may lead to arbitrary code execution.

CWE(s)
CWE-190
KEV Date Added
05 March 2026

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2022-32893Same product: Apple Ipadosboth on KEV
CVE-2021-30663Same product: Apple Ipadosboth on KEV
CVE-2025-6558Same product: Apple Ipadosboth on KEV
CVE-2023-32434Same product: Apple Ipadosboth on KEV
CVE-2021-1789Same product: Apple Ipadosboth on KEV
CVE-2023-42916Same product: Apple Ipadosboth on KEV
CVE-2023-2136Same product: Debian Debian Linuxboth on KEV
CVE-2023-42917Same product: Apple Ipadosboth on KEV
CVE-2021-30860Same product: Apple Ipadosboth on KEV
CVE-2023-6345Same product: Debian Debian Linuxboth on KEV

Affected Assets

apple
safari
≤ 15.2
apple
ipados
≤ 15.2
apple
iphone os
≤ 15.2
apple
macos
12.0 — 12.1
apple
tvos
≤ 15.2
apple
watchos
≤ 8.3
fedoraproject
fedora
34, 35
debian
debian linux
10.0, 11.0
webkitgtk
webkitgtk
≤ 2.34.4
wpewebkit
wpe webkit
≤ 2.34.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.2.6

Mitigating Controls (NIST CSF 2.0) AI

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

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect integer overflows before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates input validation and arithmetic checks that prevent integer overflows.

A.8.26 Application security requirements partial match
degrades

Application security requirements include bounds checking and safe arithmetic to avoid overflow conditions.

A.8.27 Secure system architecture and engineering principles partial match
degrades

Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe integer operations and mandate overflow-safe constructs.

References