CVE-2021-21897Public exploitNetwork attack vector

Code execution via unchecked negative vertex index

Published Sep 8, 2021 · Updated Aug 3, 2024

Heap buffer overflow in RibbonSoft dxflib 3.17.0 allows attackers to execute code when a consuming application parses a crafted DXF file. DL_Dxf::handleLWPolylineData accepts group code 42 while vertexIndex remains -1, then writes an attacker-controlled double eight bytes before the allocated vertex buffer. The file must reach an application that invokes the library's DXF parser, and parsing can corrupt heap metadata and execute code in that application's context.

CVSS severity8.8
High
EPSS probability2.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in RibbonSoft dxflib 3.17.0 allows attackers to execute code when a consuming application parses a crafted DXF file. DL_Dxf::handleLWPolylineData accepts group code 42 while vertexIndex remains -1, then writes an attacker-controlled double eight bytes before the allocated vertex buffer. The file must reach an application that invokes the library's DXF parser, and parsing can corrupt heap metadata and execute code in that application's context.

The record

CVE
CVE-2021-21897
Published
Sep 8, 2021
Updated
Aug 3, 2024
Vendor
RibbonSoft
Product
dxflib
Classifications
CWE-191, T1204.002, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Ribbonsoft dxflib 3.17.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

RibbonSoft · dxflibversion=Ribbonsoft dxflib 3.17.0

Published CVSS scores

8.8Cisco TalosCVSS:3.0/AV:N/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
8.8NIST NVDCVSS:3.1/AV:N/AC:L/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 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-191Integer Underflow (Wrap or Wraparound)
T1204.002Malicious File
T1203Exploitation for Client Execution

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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