Impact

A potential timing attack exists on pages or documents that have been protected with a shared password through Wagtail's "Privacy" controls. This password check is performed through a character-by-character string comparison, and so an attacker who is able to measure the time taken by this check to a high degree of accuracy could potentially use timing differences to gain knowledge of the password. (This is understood to be feasible on a local network, but not on the public internet.)

Privacy settings that restrict access to pages / documents on a per-user or per-group basis (as opposed to a shared password) are unaffected by this vulnerability.

Patches

Patched versions have been released as Wagtail 2.7.3 (for the LTS 2.7 branch), Wagtail 2.8.2 and Wagtail 2.9.

Workarounds

Site owners who are unable to upgrade to the new versions can use user- or group-based privacy restrictions to restrict access to sensitive information; these are unaffected by this vulnerability.

Acknowledgements

Many thanks to Thibaud Colas for reporting this issue.

For more information

If you have any questions or comments about this advisory:

• Visit Wagtail's support channels
• Email us at security@wagtail.io (if you wish to send encrypted email, the public key ID is 0x6ba1e1a86e0f8ce8)