CVE-2020-1073Network attack vector

Remote code execution via missed JIT type transition

Published Jun 9, 2020 · Updated Aug 4, 2024

Memory corruption in Microsoft Edge Legacy and ChakraCore allows remote attackers to execute code through crafted JavaScript objects. The JIT loop prepass can miss a non-optimized StFld that changes an object's type, causing downstream AdjustObjType handling to use an invalid type transition. Exploitation requires attacker-controlled JavaScript to reach the affected optimization path, and successful exploitation runs code in the hosting process.

CVSS severity8.1
High
EPSS probability8.64%
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 through crafted JavaScript objects. The JIT loop prepass can miss a non-optimized StFld that changes an object's type, causing downstream AdjustObjType handling to use an invalid type transition. Exploitation requires attacker-controlled JavaScript to reach the affected optimization path, and successful exploitation runs code in the hosting process.

The record

CVE
CVE-2020-1073
Published
Jun 9, 2020
Updated
Aug 4, 2024
Vendor
Microsoft
Product
Microsoft Edge Legacy
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Edge Legacyversion=unspecified
Microsoft · ChakraCoreversion=unspecified

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3NIST NVDAV:N/AC:M/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 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.

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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