CVE-2020-21834Network attack vector

Process crash via crafted DWG thumbnail

Published May 17, 2021 · Updated Jul 9, 2026

Null pointer dereference in get_bmp in GNU LibreDWG 0.10 allows remote attackers to crash dwgbmp via a crafted DWG file. The public record identifies dwgbmp.c line 164 as the dereference locus but does not disclose which pointer becomes null or the exact unchecked operation. Exploitation requires a user to process attacker-supplied DWG content, and the demonstrated consequence is a process crash rather than data access or 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 get_bmp in GNU LibreDWG 0.10 allows remote attackers to crash dwgbmp via a crafted DWG file. The public record identifies dwgbmp.c line 164 as the dereference locus but does not disclose which pointer becomes null or the exact unchecked operation. Exploitation requires a user to process attacker-supplied DWG content, and the demonstrated consequence is a process crash rather than data access or code execution.

The record

CVE
CVE-2020-21834
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

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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