[BALUG-Admin] Unauthenticated subscriptions to Mailman prior to v. 2.1.16
Tue Jul 26 02:05:56 UTC 2022
Here is what I was thinking of, a security weakness in Mailman's WebUI
for subscribing, that permitted spammers to sneak arbitrary addresses
onto a Mailman list's roster by generating forged POST datastreams from
offsite. Description of the bugfix, which was merged starting
There is a new mm_cfg.py setting SUBSCRIBE_FORM_SECRET which will put
a dynamically generated, hidden hash in the listinfo subscribe
form and check it upon submission. Setting this will prevent automated
processes (bots) from successfully POSTing web subscribes without first
retrieving and parsing the form from the listinfo page. The form must also be
submitted no later than FORM_LIFETIME nor no earlier than
SUBSCRIBE_FORM_MIN_TIME after retrieval. Note that enabling this
will break any static subscribe forms on your site. See the description
in Defaults.py for more info
SUBSCRIBE_FORM_SECRET must be set to "write your own string here"
in mm_cfg.py (a site-specific hash written by the site admin.
Mailman then embeds a CSRF (cross-site request forgery) token into its
subscription form. Mailman will also enforce that the form be submitted
at least five seconds after it was generated.
Michael, please confirm that is set.
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