CVE-2020-21835Public exploitNetwork attack vector

Application crash via invalid compressed-section pointer

Published May 17, 2021 · Updated Jul 9, 2026

NULL pointer dereference in GNU LibreDWG 0.10 allows context-dependent attackers to crash DWG-processing applications via a crafted DWG file. The read_2004_compressed_section function passes an invalid input-derived address to memcpy while decoding an R2004 summary section. Processing requires an application linked to LibreDWG to open the file; the demonstrated consequence is a process crash, not code execution.

CVSS severity6.5
Medium
EPSS probability0.86%
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 allows context-dependent attackers to crash DWG-processing applications via a crafted DWG file. The read_2004_compressed_section function passes an invalid input-derived address to memcpy while decoding an R2004 summary section. Processing requires an application linked to LibreDWG to open the file; the demonstrated consequence is a process crash, not code execution.

The record

CVE
CVE-2020-21835
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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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
T1204.002Malicious 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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