CVE-2021-39220

Bypass of image blocking in Nextcloud Mail

LOW
3.5
CVSS Score
Published: October 25, 2021 at 06:55 PM UTC
Updated: June 17, 2026 at 04:03 AM UTC
1 product affected across 1 vendorMail

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Severity
LOW3.5
Exploit prediction
EPSS 0.9%

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mail· Nextcloudnextcloud-app
95%
v < 1.10.4
Affected range stops below 1.10.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

CVSS

3.5LOWGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-20CWE-200

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