CVE-2020-21817Public exploitNetwork attack vector

Application crash via null TEXT pointer dereference

Published May 17, 2021 · Updated Jul 9, 2026

Null pointer dereference in GNU LibreDWG 0.10.2641 allows attackers to crash dwg2SVG through a crafted DWG file. The output_TEXT path passes decoded TEXT data to htmlescape, where strlen reads through a null source pointer at programs/escape.c:29. A user must process the file with dwg2SVG; the demonstrated result is an application crash, not code execution or data disclosure.

CVSS severity6.5
Medium
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null pointer dereference in GNU LibreDWG 0.10.2641 allows attackers to crash dwg2SVG through a crafted DWG file. The output_TEXT path passes decoded TEXT data to htmlescape, where strlen reads through a null source pointer at programs/escape.c:29. A user must process the file with dwg2SVG; the demonstrated result is an application crash, not code execution or data disclosure.

The record

CVE
CVE-2020-21817
Published
May 17, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record 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

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.

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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-476NULL Pointer Dereference
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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