https://github.com/rails/rails: Inefficient Regular Expression Complexity
CVE-2023-22795 is a high-severity inefficient regular expression complexity vulnerability in https://github.com/rails/rails, 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/rails/rails versions: 6.1.7.1, 7.0.4.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.28% chance of exploitation within 30 days, higher than 83% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Rails to 6.1.7.1 or 7.0.4.1, whichever matches your release line, or a later version.
- Read the advisory on discuss.rubyonrails.org for workarounds and exact fixed builds.
- 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/rails/rails | https://github.com/rails/rails | 6.1.7.1, 7.0.4.1 | Not stated |
| Rubyonrails | Rails | before 6.1.7.1; 7.0.0 up to, but not including, 7.0.4.1 | 6.1.7.1, 7.0.4.1 |
| Debian | Debian Linux | 11.0 | Not stated |
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 regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-Match header. A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophic backtracking, when on a version of Ruby below 3.2.0. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should either upgrade or use one of the workarounds immediately.
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
- debian.org/security/2023/dsa-5372Third Party Advisory
Other references
Other vulnerabilities in https://github.com/rails/rails
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 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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