CVE-2020-19693Public exploitNetwork attack vector

Code execution via unchecked oldFunc pointer

Published Apr 4, 2023 · Updated Feb 18, 2025

Memory corruption in Espruino 6ea4c0a allows remote attackers to execute arbitrary code through a crafted replaceWith call. jswrap_function_replaceWith validates only newFunc, then treats oldFunc as a JsVar pointer and writes to its flags field without checking its type or validity. The attacker must be able to invoke Espruino JavaScript; a null oldFunc crashes the interpreter, while a chosen address enables memory writes and code execution.

CVSS severity9.8
Critical
EPSS probability0.83%
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 Espruino 6ea4c0a allows remote attackers to execute arbitrary code through a crafted replaceWith call. jswrap_function_replaceWith validates only newFunc, then treats oldFunc as a JsVar pointer and writes to its flags field without checking its type or validity. The attacker must be able to invoke Espruino JavaScript; a null oldFunc crashes the interpreter, while a chosen address enables memory writes and code execution.

The record

CVE
CVE-2020-19693
Published
Apr 4, 2023
Updated
Feb 18, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 18, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write

Public exploit references

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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