Remote code execution via JavaScriptCore type confusion
Published Jul 29, 2025 · Updated Aug 27, 2026
Type confusion in WebKit on affected Apple platforms allows remote attackers to corrupt memory through malicious web content. JavaScriptCore's JIT optimizer mishandles type information, enabling fake-object and address-of primitives that build arbitrary read and write. A user must load attacker-controlled content; observed DarkSword chains turn the flaw into remote code execution inside Safari's WebContent sandbox.
Summary
What happened
Type confusion in WebKit on affected Apple platforms allows remote attackers to corrupt memory through malicious web content. JavaScriptCore's JIT optimizer mishandles type information, enabling fake-object and address-of primitives that build arbitrary read and write. A user must load attacker-controlled content; observed DarkSword chains turn the flaw into remote code execution inside Safari's WebContent sandbox.
The record
- CVE
- CVE-2025-31277
- Published
- Jul 29, 2025
- Updated
- Aug 27, 2026
- Vendor
- Apple
- Product
- iOS and iPadOS
- Classifications
- CWE-119, CWE-120, T1203, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 29, 2025CVE publishedPublication date reported by the CVE source.
- Mar 20, 2026Exploitation reportedCISA Known Exploited Vulnerabilities listing
- Aug 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <18.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- DarkSword rce_module.jsweaponized · observed in use
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- Multiple threat actors using DarkSwordthreat actor
- CISA Known Exploited Vulnerabilities listingknown exploited catalog
- DarkSword iOS exploit chainexploit chain
Technologies
Your stack
See the directory against your own environment.
Your stack
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