CVE-2020-1065Network attack vector

Code execution via incorrect captured-scope indexing

Published May 21, 2020 · Updated Aug 19, 2026

Memory corruption in Microsoft Edge Legacy and ChakraCore allows remote attackers to execute code via crafted JavaScript content. ScopeInfo.cpp omits an enclosing body scope when a nested function is declared in a merged parameter scope, causing captured symbols to receive an incorrect envIndex. Exploitation requires user interaction with attacker-controlled content and runs code with the current user's rights.

CVSS severity4.2
Medium
EPSS probability2.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in Microsoft Edge Legacy and ChakraCore allows remote attackers to execute code via crafted JavaScript content. ScopeInfo.cpp omits an enclosing body scope when a nested function is declared in a merged parameter scope, causing captured symbols to receive an incorrect envIndex. Exploitation requires user interaction with attacker-controlled content and runs code with the current user's rights.

The record

CVE
CVE-2020-1065
Published
May 21, 2020
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Microsoft Edge Legacy
Classifications
CWE-787, T1203
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 · Microsoft Edge Legacyversion=1.0..0 <publication
Microsoft · ChakraCoreversion=0 <publication

Published CVSS scores

4.2MicrosoftCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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