https://github.com/rack/rack: Inefficient Regular Expression Complexity
CVE-2022-44572 is a high-severity inefficient regular expression complexity vulnerability in https://github.com/rack/rack, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected https://github.com/rack/rack versions: 2.0.9.2, 2.1.4.2, 2.2.4.1, 3.0.0.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.62% chance of exploitation within 30 days, higher than 76% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Rack to 2.0.9.2 or 2.1.4.2 or 2.2.4.1, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Https://github.com/rack/rack | https://github.com/rack/rack | 2.0.9.2, 2.1.4.2, 2.2.4.1, 3.0.0.1 | Not stated |
| Rack | Rack | before 2.0.9.2; 2.1.0 up to, but not including, 2.1.4.2; 2.2.0 up to, but not including, 2.2.4.1 | 2.0.9.2, 2.1.4.2, 2.2.4.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
Official description
A denial of service vulnerability in the multipart parsing component of Rack fixed in 2.0.9.2, 2.1.4.2, 2.2.4.1 and 3.0.0.1 could allow an attacker tocraft input that can cause RFC2183 multipart boundary parsing in Rack to take an unexpected amount of time, possibly resulting in a denial of service attack vector. Any applications that parse multipart posts using Rack (virtually all Rails applications) are impacted.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Inefficient Regular Expression Complexity
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
How developers prevent this class of flaw
- Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
- Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
- Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
More Inefficient Regular Expression Complexity vulnerabilities (CWE-1333)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- hackerone.com/reports/1639882Permissions Required, Third Party Advisory
Other vulnerabilities in https://github.com/rack/rack
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 10.0 Critical severity
Recent Inefficient Regular Expression Complexity vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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