CyberSecBulletin
CVE-2025-24201Exploited in the wildNVD status: Analyzed

Apple Multiple Products WebKit Out-of-Bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2025-24201 is a critical-severity out-of-bounds write vulnerability in Safari from Apple, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 18.3.1 as the first without the flaw, so updating Safari to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on March 13, 2025, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Safari to 18.3.1 or a later version.
  2. Update iOS and iPadOS to 15.8.4 or 16.7.11 or 18.3.2, whichever matches your release line, or a later version.
  3. Update iPadOS to 17.7.6 or a later version.
  4. CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  5. Read the advisory on support.apple.com for workarounds and exact fixed builds.
  6. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
AppleSafaribefore 18.3.118.3.1
AppleiOS and iPadOSbefore 15.8.4; before 16.7.11; before 18.3.215.8.4, 16.7.11, 18.3.2
AppleiPadOSbefore 17.7.617.7.6
ApplemacOSbefore 15.3.215.3.2
ApplevisionOSbefore 2.3.22.3.2
ApplewatchOSbefore 11.411.4
AppleIphone OS15.8 up to, but not including, 15.8.4; 16.7 up to, but not including, 16.7.11; 17.0 up to, but not including, 18.3.215.8.4, 16.7.11, 18.3.2
DebianDebian Linux11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.110.0CriticalNVD
CVSS 3.110.0CriticalCISA (ADP)

Official description

An out-of-bounds write issue was addressed with improved checks to prevent unauthorized actions. This issue is fixed in Safari 18.3.1, iOS 15.8.4 and iPadOS 15.8.4, iOS 16.7.11 and iPadOS 16.7.11, iOS 18.3.2 and iPadOS 18.3.2, iPadOS 17.7.6, macOS Sequoia 15.3.2, visionOS 2.3.2, watchOS 11.4. Maliciously crafted web content may be able to break out of Web Content sandbox. This is a supplementary fix for an attack that was blocked in iOS 17.2. (Apple is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals on versions of iOS before iOS 17.2.).

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Safari

All Safari vulnerabilities

Recent Out-of-bounds Write vulnerabilities

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