CyberSecBulletin
CVE-2023-39928NVD status: Modified

Webkit: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2023-39928 is a high-severity use after free vulnerability in Webkit, 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. Affected Webkit versions: WebKitGTK 2.40.5. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.45% chance of exploitation within 30 days, higher than 74% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Webkit you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on webkitgtk.org for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  4. 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

VendorProductAffected versionsFixed in
WebkitWebkitWebKitGTK 2.40.5Not stated
WebkitgtkWebkitgtk2.40.5Not stated
DebianDebian Linux11.0; 12.0Not stated
Fedora ProjectFedora37Not 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
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 systemScoreSeverityScored by
CVSS 3.18.8HighCNA (cisco.com)
CVSS 3.18.8HighNVD

Official description

A use-after-free vulnerability exists in the MediaRecorder API of Webkit WebKitGTK 2.40.5. A specially crafted web page can abuse this vulnerability to cause memory corruption and potentially arbitrary code execution. A user would need to to visit a malicious webpage to trigger this vulnerability.

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.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Webkit

All Webkit vulnerabilities

Recent Use After Free vulnerabilities

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