CVE-2021-32707

Public Exploit
Bypass of image blocking in Nextcloud Mail

Description

Nextcloud Mail is a mail app for Nextcloud. In versions prior to 1.9.6, the Nextcloud Mail application does not, by default, render images in emails to not leak the read state. The privacy filter failed to filter images with a `background-image` CSS attribute. Note that the images were still passed through the Nextcloud image proxy, and thus there was no IP leakage. The issue was patched in version 1.9.6 and 1.10.0. No workarounds are known to exist.

Category

4.3
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.64%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory hackerone.com
Affected: nextcloud security-advisories
Published at:
Updated at:

References

Link Tags
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xxp4-44xc-8crh third party advisory
https://github.com/nextcloud/mail/pull/5189 third party advisory patch
https://hackerone.com/reports/1215251 third party advisory exploit

Frequently Asked Questions

What is the severity of CVE-2021-32707?
CVE-2021-32707 has been scored as a medium severity vulnerability.
How to fix CVE-2021-32707?
To fix CVE-2021-32707, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-32707 being actively exploited in the wild?
It is possible that CVE-2021-32707 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~1% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-32707?
CVE-2021-32707 affects nextcloud security-advisories.
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