Apple Multiple Products WebKit Use-After-Free
CVE-2023-32373 is a high-severity use after free vulnerability in macOS from Apple, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 13.4 as the first without the flaw, so updating macOS to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on May 22, 2023, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update macOS to 13.4 or a later version.
- Update Safari to 16.5 or a later version.
- Update watchOS to 9.5 or a later version.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on support.apple.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apple | macOS | before 13.4 | 13.4 |
| Apple | Safari | before 16.5 | 16.5 |
| Apple | watchOS | before 9.5 | 9.5 |
| Apple | iOS and iPadOS | before 15.7; before 16.5 | 15.7, 16.5 |
| Apple | tvOS | before 16.5 | 16.5 |
| Apple | iPadOS | before 15.7.6; 16.0 up to, but not including, 16.5 | 15.7.6, 16.5 |
| Apple | Iphone OS | 15.0 up to, but not including, 15.7.6; 16.0 up to, but not including, 16.5 | 15.7.6, 16.5 |
| Red Hat | Enterprise Linux | 6.0; 7.0; 8.0; 9.0 | Not stated |
| Webkitgtk | Webkitgtk+ | before 2.42.3 | 2.42.3 |
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
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- 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:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | NVD |
| CVSS 3.1 | 8.8 | High | CISA (ADP) |
Official description
A use-after-free issue was addressed with improved memory management. This issue is fixed in watchOS 9.5, tvOS 16.5, macOS Ventura 13.4, iOS 15.7.6 and iPadOS 15.7.6, Safari 16.5, iOS 16.5 and iPadOS 16.5. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- support.apple.com/en-us/HT213757Release Notes
- support.apple.com/en-us/HT213758Release Notes
- support.apple.com/en-us/HT213761Release Notes
- support.apple.com/en-us/HT213762Release Notes
- support.apple.com/en-us/HT213764Release Notes
- support.apple.com/en-us/HT213765Release Notes
Third-party and government advisories
- security.gentoo.org/glsa/202401-04Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-32373US Government Resource
Other vulnerabilities in macOS
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Use After Free vulnerabilities
- 7.1 High severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.1 High severity
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