CVE-2021-29326Public exploit

Process crash via oversized identifier conversion

Published Nov 19, 2021 · Updated Aug 3, 2024

A heap buffer overflow in fxIDToString in OpenSource Moddable 10.5.0 allows local users to corrupt memory via crafted JavaScript. When XS converts a crafted identifier to text, fxIDToString writes 3,349 bytes past a 1,456-byte heap allocation in xsSymbol.c. The user must run the crafted script with xst, and the demonstrated consequence is process abort after heap corruption.

CVSS severity7.8
High
EPSS probability0.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A heap buffer overflow in fxIDToString in OpenSource Moddable 10.5.0 allows local users to corrupt memory via crafted JavaScript. When XS converts a crafted identifier to text, fxIDToString writes 3,349 bytes past a 1,456-byte heap allocation in xsSymbol.c. The user must run the crafted script with xst, and the demonstrated consequence is process abort after heap corruption.

The record

CVE
CVE-2021-29326
Published
Nov 19, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File

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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