CVE-2020-23257Public exploitNetwork attack vector

Unauthenticated service crash via garbage-collector type confusion

Published Apr 4, 2023 · Updated Feb 13, 2025

Buffer overflow in Espruino 2.05.41 allows remote attackers to crash the interpreter by supplying crafted JavaScript input. During garbage collection, src/jsvar.c's jsvGarbageCollectMarkUsed treats an object property name as a native-string structure, follows attacker-controlled content, and writes through the resulting invalid address. No authentication or user interaction is required; successful execution terminates the interpreter with a segmentation fault, interrupting hosted service or device logic.

CVSS severity7.5
High
EPSS probability0.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Espruino 2.05.41 allows remote attackers to crash the interpreter by supplying crafted JavaScript input. During garbage collection, src/jsvar.c's jsvGarbageCollectMarkUsed treats an object property name as a native-string structure, follows attacker-controlled content, and writes through the resulting invalid address. No authentication or user interaction is required; successful execution terminates the interpreter with a segmentation fault, interrupting hosted service or device logic.

The record

CVE
CVE-2020-23257
Published
Apr 4, 2023
Updated
Feb 13, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

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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