CVE-2021-29421: models/metadata.py in the pikepdf package 1.3.0 through 2.9.2 for Python allows XXE when parsing XMP metadata

This month

HIGH 7.5REMOTEUPGRADEMITIGATE

CVE-2021-29421 is a high-severity flaw (CVSS 7.5) affecting pikepdf, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

models/metadata.py in the pikepdf package 1.3.0 through 2.9.2 for Python allows XXE when parsing XMP metadata entries.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-611
Published	2021-04-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · pikepdf project

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

Am I affected?

Timeline

2021-04-01 20:15 UTCPublished CVE record published
2026-06-17 03:47 UTCUpdated Record last modified

pikepdf project pikepdf UPGRADE

Affected: >= 1.3.0 and <= 2.9.2

Fixed in: newer than 2.9.2

Safe to downgrade to: a release before 1.3.0

1. Check installed version

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

2. UPGRADE to newer than 2.9.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade pikepdf

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade pikepdf

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.3.0 (Debian / Ubuntu)

apt-cache madison pikepdf sudo apt install pikepdf=<VERSION_BEFORE_1.3.0> sudo apt-mark hold pikepdf

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list pikepdf sudo dnf downgrade pikepdf-<VERSION_BEFORE_1.3.0> sudo dnf versionlock add pikepdf

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

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.

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-2021-29421?

pikepdf: upgrade to newer than 2.9.2; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-29421 being exploited?

CVE-2021-29421 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-2021-29421 affect?

CVE-2021-29421 affects pikepdf, fedora. Severity is high (CVSS 7.5). models/metadata.py in the pikepdf package 1.3.0 through 2.9.2 for Python allows XXE when parsing XMP metadata entries.

How urgent is CVE-2021-29421?

Priority 50/100. High severity; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

References

← Back to latest CVEs