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nextcloudNextcloudGHSA-XXP4-44XC-8CRH
HistoryJul 12, 2021 - 9:20 a.m.

Bypass of image blocking in Nextcloud Mail

2021-07-1209:20:58
github.com
19

4 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:L/Au:S/C:N/I:P/A:N

4.3 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

NONE

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

0.001 Low

EPSS

Percentile

30.6%

Description

Impact

The Nextcloud Mail application does by default not 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.

Patches

It is recommended that the Nextcloud Mail application is upgraded to 1.9.6 or 1.10.0

Workarounds

None.

References

For more information

If you have any questions or comments about this advisory:

CPENameOperatorVersion
nextcloud maillt1.9.6
nextcloud maillt1.10.0

4 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:L/Au:S/C:N/I:P/A:N

4.3 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

NONE

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

0.001 Low

EPSS

Percentile

30.6%

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