CVE-2021-39220: Nextcloud is an open-source, self-hosted productivity platform The Nextcloud Mail application prior to version

Q: How do I fix CVE-2021-39220?

mail: upgrade to 1.10.4. Exact commands for each OS are on this page.

Q: Is CVE-2021-39220 being exploited?

CVE-2021-39220 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-39220 affect?

CVE-2021-39220 affects mail. Severity is low (CVSS 3.5). Nextcloud is an open-source, self-hosted productivity platform The Nextcloud Mail application prior to versions 1.10.4 and 1.11.0 does by default not render images in emails to not leak the read state or user IP. The privacy filter failed t

Q: How urgent is CVE-2021-39220?

Priority 27/100. No elevated risk signals yet.

Routine

LOW 3.5UPGRADE

CVE-2021-39220 is a low-severity flaw (CVSS 3.5) affecting mail. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Nextcloud is an open-source, self-hosted productivity platform The Nextcloud Mail application prior to versions 1.10.4 and 1.11.0 does by default not render images in emails to not leak the read state or user IP. The privacy filter failed to filter images with a relative protocol. It is recommended that the Nextcloud Mail application is upgraded to 1.10.4 or 1.11.0. There are no known workarounds aside from upgrading.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	3.5 (Low)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-20, CWE-200
Published	2021-10-25
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: nextcloud

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

Am I affected?

Timeline

2021-10-25 19:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

nextcloud mail UPGRADE

Affected: < 1.10.4

Fixed in: 1.10.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.10.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mail

Note

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

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-2021-39220?

mail: upgrade to 1.10.4. Exact commands for each OS are on this page.

Is CVE-2021-39220 being exploited?

CVE-2021-39220 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-2021-39220 affect?

CVE-2021-39220 affects mail. Severity is low (CVSS 3.5). Nextcloud is an open-source, self-hosted productivity platform The Nextcloud Mail application prior to versions 1.10.4 and 1.11.0 does by default not render images in emails to not leak the read state or user IP. The privacy filter failed t

How urgent is CVE-2021-39220?

Priority 27/100. No elevated risk signals yet.

Software pages

Nextcloud vulnerabilities

Related CVEs

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CVE-2023-48307 LOW 3.5 UPGRADE Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity platform
CVE-2023-45660 MEDIUM 4.3 UPGRADE Nextcloud mail is an email app for the Nextcloud home server platform

References

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