CVE-2021-39220

Bypass of image blocking in Nextcloud Mail

CVSS 3.5 LOWEPSS 0.8%CWE-20 CWE-200

Vexday Risk Score

8Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 3.5EPSS 0.8%KEV nãoPoC —Patch —

Lifecycle

25 Oct 2021Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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.

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N

Affected products

nextcloud · security-advisories

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References

https://github.com/nextcloud/mail/pull/5470 https://github.com/nextcloud/security-advisories/security/advisories/GHSA-6q9v-wm8r-rcv5 https://hackerone.com/reports/1308147