CVE-2020-1062Network attack vector

User-context code execution via JScript use-after-free

Published May 21, 2020 · Updated Aug 19, 2026

Use-after-free in JScript garbage collection in Microsoft Internet Explorer 9 and 11 allows remote attackers to execute code via crafted content. JScript actions can make garbage collection free an object while retaining its pointer, which jscript.dll later reuses in the browser process. Exploitation requires the current user to visit a malicious page or open a malicious file, and resulting code receives that user's rights.

CVSS severity8.1
High
EPSS probability6.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in JScript garbage collection in Microsoft Internet Explorer 9 and 11 allows remote attackers to execute code via crafted content. JScript actions can make garbage collection free an object while retaining its pointer, which jscript.dll later reuses in the browser process. Exploitation requires the current user to visit a malicious page or open a malicious file, and resulting code receives that user's rights.

The record

CVE
CVE-2020-1062
Published
May 21, 2020
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Internet Explorer 11
Classifications
CWE-119, T1204.002, T1203, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <publication

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Internet Explorer 11version=1.0.0 <publication
Microsoft · Internet Explorer 9version=1.0.0 <publication

Published CVSS scores

8.1NISTCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8Zero Day InitiativeCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
9.3NISTAV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1204.002Malicious File
T1203Exploitation for Client Execution
T1204.001Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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