Attacker Value
Moderate
(1 user assessed)
Exploitability
Moderate
(1 user assessed)
User Interaction
Unknown
Privileges Required
Unknown
Attack Vector
Unknown
1

CVE-2021-26419

Disclosure Date: May 11, 2021 •
CVE-2021-26419
Exploited in the Wild
Reported by gwillcox-r7
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Initial Access
Techniques
Validation
Validated

Description

Scripting Engine Memory Corruption Vulnerability

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2
Ratings
  • Attacker Value
    Medium
  • Exploitability
    Medium
Common in enterpriseRequires user interaction
Technical Analysis

Details

The vulnerability affects Internet Explorer 11 on all Windows Versions. It is located in the jscript9.dll library, which is used to execute javascript.

Possible attack vectors:

  • website content
  • activeX components in office documents

Google Project Zero released a PoC on 13.05.2021, which triggers the vulnerability and causes a crash. At the time of writing I could not find any weaponized exploit.

The CVSS rating of the vulnerability differs between Windows desktop versions and server versions. In server versions the CVSS Privileges Required is set to High. Desktop versions are rated with CVSS None. The reason could be, that IE enhanced protection mode is disabled on Windows desktop versions and enabled on server versions by default.

Rating explanation

My rating of the exploitability score was affected by the availability of the PoC and the Microsoft exploitability rating. In year 2020, Operation PowerFall was using a similar vulnerability (CVE-2020-1380) in IE. I expect to see exploits for CVE-2021-26419 in a similar context.

Attackers might gain direct control over the host after exploitation without a sandbox escape. IE 11 does have a enhanced protected mode (EPM), which runs IE in an AppContainer and acts as a sandbox. EPM was introduced with Windows 8 and is disabled by default on Windows desktop versions.

Sources

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CVSS V3 Severity and Metrics
Base Score:
None
Impact Score:
Unknown
Exploitability Score:
Unknown
Vector:
Unknown
Attack Vector (AV):
Unknown
Attack Complexity (AC):
Unknown
Privileges Required (PR):
Unknown
User Interaction (UI):
Unknown
Scope (S):
Unknown
Confidentiality (C):
Unknown
Integrity (I):
Unknown
Availability (A):
Unknown

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Internet Explorer 11 10.0.14393.4401
Internet Explorer 9 6.0.6003.21117
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • microsoft

Products

  • internet explorer 11,
  • internet explorer 9

Exploited in the Wild

Reported by:

Additional Info

Authenticated
Unknown
Exploitable
Unknown
Reliability
Unknown
Stability
Unknown
Available Mitigations
Unknown
Shelf Life
Unknown
Userbase/Installbase
Unknown
Patch Effectiveness
Unknown
Technical Analysis