CyberSecBulletin
CVE-2013-3893Exploited in the wildNVD status: Analyzed

Microsoft Internet Explorer Resource Management Errors

Published Updated By the CyberSecBulletin desk

CVE-2013-3893 is a high-severity use after free vulnerability in Internet Explorer from Microsoft, with a CVSS 2.0 base score of 9.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Internet Explorer versions: 6; 7; 8, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on August 12, 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. Check which version of Internet Explorer you run against the affected versions below, and install the vendor's latest release.
  2. 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.
  3. Read the advisory on blogs.technet.com for workarounds and exact fixed builds.
  4. 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
MicrosoftInternet Explorer6; 7; 8; 9; 10; 11Not stated

Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Access vector
NetworkCan be exploited remotely over a network.
Access complexity
MediumSome conditions must be met.
Authentication
NoneNo login is needed.
Confidentiality
CompleteAll data can be read.
Integrity
CompleteAny data can be modified.
Availability
CompleteThe system can be shut down completely.

Vector: AV:N/AC:M/Au:N/C:C/I:C/A:C. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCISA (ADP)
CVSS 2.09.3HighNVD

Official description

Use-after-free vulnerability in the SetMouseCapture implementation in mshtml.dll in Microsoft Internet Explorer 6 through 11 allows remote attackers to execute arbitrary code via crafted JavaScript strings, as demonstrated by use of an ms-help: URL that triggers loading of hxds.dll.

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. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  3. Added to CISA's Known Exploited Vulnerabilities catalogue.
  4. Deadline for US federal agencies to remediate, set by CISA.
  5. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Internet Explorer

All Internet Explorer vulnerabilities

Recent Use After Free vulnerabilities

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