The parsing team has fixed a security bug in Parsoid [1].
* Users could send invalid prefixes, formats, or domains and run
javascript code on the error page that Parsoid displayed.
* This fix has been applied to the Wikimedia cluster [2] and also merged
into Parsoid master [1].
* We have also released a 0.5.3 deb version with this patch applied. [3]
* We have also released a 0.5.3 npm version of Parsoid. [4]
* Parsoid is a stateless service and doesn't retain any state between
requests. In private wikis, VisualEditor can be configured to
forward the user cookie to Parsoid to pass along to the MediaWiki API
to parse a page, but this exploit is not exposed through VE.
In addition, Parsoid doesn't receive any user credentials on public
wikis.
* However, if a wiki's Parsoid service is publicly accessible on the
internet
*and* is accessible through the wiki's domain, then, this exploit can be
used to leak user cookies for that wiki. For all wikis that use Parsoid
in this fashion, we recommend they patch their Parsoid installation
immediately.
* On the Wikimedia cluster, Parsoid is proxied behind RESTBase and is
not public accessible and as such, this exploit wasn't available for
an exploit to steal user sessions.
Thanks to the reporter of this exploit, Darian Patrick from the Security
Team,
Arlo Breault from the Parsing Team, Daniel Zahn and others from Ops for
their
assistance handling this bug and preparing this release.
[1]
https://gerrit.wikimedia.org/r/#/c/319115
[2]
https://www.mediawiki.org/wiki/Parsoid/Deployments#Monday.2C_October_31.2C_…
[3]
https://releases.wikimedia.org/debian/pool/main/p/parsoid/
[4]
https://www.npmjs.com/package/parsoid
Subramanya Sastry,
Technical Lead and Manager,
Parsing Team,
Wikimedia Foundation.