CVE-2021-21772: A use-after-free vulnerability exists in the NMR::COpcPackageReader::releaseZIP() functionality of 3MF Consort

This week

HIGH 8.1REMOTEWATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2021-21772 is a high-severity flaw (CVSS 8.1) affecting lib3mf, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A use-after-free vulnerability exists in the NMR::COpcPackageReader::releaseZIP() functionality of 3MF Consortium lib3mf 2.0.0. A specially crafted 3MF file can lead to code execution. An attacker can provide a malicious file to trigger this vulnerability.

Why this priority

High severity
EPSS top 9%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

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

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	4.2% (top 9%)
CISA exploited list	No
Weakness	CWE-416
Published	2021-03-10
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: 3mf · debian · fedoraproject

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

Am I affected?

Timeline

2021-03-10 17:15 UTCPublished CVE record published
2026-06-17 03:36 UTCUpdated Record last modified

3mf lib3mf DOWNGRADE

Affected: 2.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy lib3mf || rpm -q lib3mf || lib3mf --version

2. No fixed release: DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison lib3mf sudo apt install lib3mf=<VERSION_BEFORE_2.0.0> sudo apt-mark hold lib3mf

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

dnf --showduplicates list lib3mf sudo dnf downgrade lib3mf-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add lib3mf

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.

fedoraproject fedora MITIGATE

Affected: 32 · 33 · 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 32

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.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

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.

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-2021-21772?

lib3mf: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-21772 being exploited?

CVE-2021-21772 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-2021-21772 affect?

CVE-2021-21772 affects lib3mf, fedora, debian linux. Severity is high (CVSS 8.1). A use-after-free vulnerability exists in the NMR::COpcPackageReader::releaseZIP() functionality of 3MF Consortium lib3mf 2.0.0. A specially crafted 3MF file can lead to code execution. An attacker can provide a malicious file to trigger thi

How urgent is CVE-2021-21772?

Priority 66/100. High severity; EPSS top 9%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

References

← Back to latest CVEs