CVE-2021-21900: A code execution vulnerability exists in the dxfRW::processLType() functionality of LibreCad libdxfrw 2.2.0-rc

This week

HIGH 8.8WATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2021-21900 is a high-severity flaw (CVSS 8.8) affecting libdxfrw, debian linux, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A code execution vulnerability exists in the dxfRW::processLType() functionality of LibreCad libdxfrw 2.2.0-rc2-19-ge02f3580. A specially-crafted .dxf file can lead to a use-after-free vulnerability. An attacker can provide a malicious file to trigger this vulnerability.

Why this priority

High severity
Public exploit reference
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-416
Published	2021-11-19
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: debian · fedoraproject · librecad

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-11-19 19:15 UTCPublished CVE record published
2026-06-17 03:36 UTCUpdated Record last modified

librecad libdxfrw DOWNGRADE

Affected: 2.2.0-rc2-19-ge02f3580

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.2.0-rc2-19-ge02f3580

1. Check installed version

apt-cache policy libdxfrw || rpm -q libdxfrw || libdxfrw --version

2. No fixed release: DOWNGRADE to a release before 2.2.0-rc2-19-ge02f3580 (Debian / Ubuntu)

apt-cache madison libdxfrw sudo apt install libdxfrw=<VERSION_BEFORE_2.2.0-rc2-19-ge02f3580> sudo apt-mark hold libdxfrw

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libdxfrw sudo dnf downgrade libdxfrw-<VERSION_BEFORE_2.2.0-rc2-19-ge02f3580> sudo dnf versionlock add libdxfrw

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 9.0 · 10.0 · 11.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

fedoraproject fedora MITIGATE

Affected: 34 · 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-21900?

libdxfrw: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-21900 being exploited?

CVE-2021-21900 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-21900 affect?

CVE-2021-21900 affects libdxfrw, debian linux, fedora. Severity is high (CVSS 8.8). A code execution vulnerability exists in the dxfRW::processLType() functionality of LibreCad libdxfrw 2.2.0-rc2-19-ge02f3580. A specially-crafted .dxf file can lead to a use-after-free vulnerability. An attacker can provide a malicious file

How urgent is CVE-2021-21900?

Priority 62/100. High severity; Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2021-21899 HIGH 8.8 DOWNGRADE MITIGATE A code execution vulnerability exists in the dwgCompressor::copyCompBytes21 functionality of LibreCad libdxfrw
CVE-2021-21898 HIGH 8.8 DOWNGRADE MITIGATE A code execution vulnerability exists in the dwgCompressor::decompress18() functionality of LibreCad libdxfrw
CVE-2018-14444 HIGH 7.5 DOWNGRADE libdxfrw 0.6.3 has an Integer Overflow in dwgCompressor::decompress18 in dwgutil.cpp, leading to an out-of-bou

References

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