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Regular Expression Denial of Service in OpenProject forum messages

Moderate
oliverguenther published GHSA-qqvp-j6gm-q56f Jul 20, 2021

Package

OpenProject

Affected versions

<= 11.3.2

Patched versions

11.3.3

Description

Impact

The MessagesController class of OpenProject has a quote method that implements the logic behind the Quote button in the discussion forums, and it uses the following regex to strip <pre> tags from the message being quoted (app/controllers/messages_controller.rb#L147):

text.to_s.strip.gsub(%r{<pre>((.|\s)*?)</pre>}m, '[...]')

The (.|\s) part can match a space character in two ways, so an unterminated <pre> tag containing n spaces causes Ruby's regex engine to backtrack to try 2n states in the NFA. This will result in a Regular Expression Denial of Service.

Patches

The vulnerability has been introduced in Redmine before forking it. It is present in all OpenProject versions up to, and including, version 11.3.2. The issue is fixed in OpenProject 11.3.3

Workarounds

The vulnerability can also be fixed by applying the following patch: https://github.com/opf/openproject/pull/9447.patch

References

For more information

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Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CVE ID

CVE-2021-32763

Weaknesses