Cross-site Scripting (XSS) - Reflected in beancount/fava


Reported on

Jun 9th 2022


The time parameter in fava is vulnerable to reflected XSS

Proof of Concept

  1. 1.Open the web browser to access the fava webpage.
  2. 2.Access the url: Script will be reflected in on clicking the button.
  3. 3.when the victim clicks on the button -> Alert box will pop up



If an attacker can control a script that is executed in the victim's browser, then they can typically fully compromise that user. Amongst other things, the attacker can:

+Perform any action within the application that the user can perform.

+View any information that the user is able to view.

+Modify any information that the user is able to modify.

Initiate interactions with other application users, including malicious attacks, that will appear to originate from the initial victim user. There are various means by which an attacker might induce a victim user to make a request that they control, to deliver a reflected XSS attack. These include placing links on a website controlled by the attacker, or on another website that allows content to be generated, or by sending a link in an email, tweet or other message

We are processing your report and will contact the beancount/fava team within 24 hours. 2 months ago
saharshtapi modified the report
2 months ago
We created a GitHub Issue asking the maintainers to create a 2 months ago
2 months ago


@admin can you please sent the magic link to the maintainers at this emails PS: This email were provided by them in one of the GitHub issues and I has also contacted them via mail and they requested to access the reports without signing up Thanks

Jamie Slome
2 months ago


Sorting this for you now ūüĎć

Jamie Slome
2 months ago


I've dropped a comment on the GitHub Issue here. I do need to get authorised confirmation from the maintainers before sending any e-mails out with magic URLs.

2 months ago


Understood. Appreciate it!!

We have opened a pull request with a for beancount/fava to merge. 2 months ago
We have contacted a member of the beancount/fava team and are waiting to hear back a month ago
Jamie Slome
a month ago


E-mail sent ūüĎć

We have sent a follow up to the beancount/fava team. We will try again in 7 days. a month ago
A beancount/fava maintainer has acknowledged this report a month ago
A beancount/fava maintainer modified the Severity from Critical (9.6) to High (8) 21 days ago
A beancount/fava maintainer modified the Severity from High to Low 21 days ago
A beancount/fava maintainer
21 days ago


Since Fava URLs are dependent on the name of the underlying Beancount journal and the base URLs, which should be private and require a previous attach to be determined by the attacker, I've marked the attack complexity as "high"

A beancount/fava maintainer modified the Severity from Low to High (8.2) 21 days ago
A beancount/fava maintainer modified the Severity from High (8.2) to High (8) 21 days ago
The researcher has received a minor penalty to their credibility for miscalculating the severity: -1
A beancount/fava maintainer validated this vulnerability 21 days ago
saharshtapi has been awarded the disclosure bounty
The fix bounty is now up for grabs
The researcher's credibility has increased: +7
A beancount/fava maintainer confirmed that a fix has been merged on ca9e38 21 days ago
The fix bounty has been dropped
A beancount/fava maintainer gave praise 21 days ago
Thank you for the report :)
The researcher's credibility has slightly increased as a result of the maintainer's thanks: +1
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