Internet Explorer JScript use-after-free remote code execution
CVE-2020-1380 is a remote code execution vulnerability in Internet Explorer 11’s scripting engine, specifically in jscript9.dll. The flaw stems from improper handling of objects in memory and has been described by multiple sources as a JScript use-after-free condition associated with JIT-optimized code paths. Exploitation can corrupt memory and allow an attacker to achieve arbitrary code execution in the context of the current user. Public reporting on active exploitation indicates the bug can be triggered through specially crafted web content rendered by Internet Explorer, including malicious or compromised websites, or content embedded via an ActiveX control marked safe for initialization in an application or Microsoft Office document hosting the IE rendering engine. Kaspersky’s reporting further states the exploit abused a JIT-related use-after-free in jscript9.dll to obtain arbitrary read/write, bypass CFG, and execute shellcode via a ROP chain.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A memory corruption vulnerability in the Windows Scripting Engine that allows remote code execution, previously exploited by ScarCruft.
An Internet Explorer client-execution vulnerability used by ScarCruft during the watering-hole attack chain that ultimately led to BLUELIGHT and then Dolphin deployment.
Internet Explorer (JScript9.dll) use-after-free vulnerability enabling remote code execution via JIT-compiled code paths that omit necessary lifetime checks for ArrayBuffer/TypedArray backing stores.
A remote code execution vulnerability in the Windows Scripting Engine that the content states has been publicly exploited.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.