Sisimai: Inefficient Regular Expression Complexity
CVE-2022-4891 is a high-severity inefficient regular expression complexity vulnerability in Sisimai, 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 Sisimai versions: 4.25.14p11. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.39% chance of exploitation within 30 days, higher than 73% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Sisimai you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
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.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 3.5 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 2.0 | 2.7 | Low | CNA (vuldb.com) |
Official description
A vulnerability has been found in Sisimai up to 4.25.14p11 and classified as problematic. This vulnerability affects the function to_plain of the file lib/sisimai/string.rb. The manipulation leads to inefficient regular expression complexity. The exploit has been disclosed to the public and may be used. Upgrading to version 4.25.14p12 is able to address this issue. The name of the patch is 51fe2e6521c9c02b421b383943dc9e4bbbe65d4e. It is recommended to upgrade the affected component. The identifier of this vulnerability is VDB-218452.
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
Patches and release notes
- github.com/sisimai/rb-sisimai/commit/51fe2e6521c9c02b421b383943dc9e4bbbe65d4eThird Party Advisory
- github.com/sisimai/rb-sisimai/pull/244Exploit, Third Party Advisory
- github.com/sisimai/rb-sisimai/releases/tag/v4.25.14p12Release Notes, Third Party Advisory
Third-party and government advisories
- vuldb.com/?ctiid.218452Permissions Required, Third Party Advisory
- vuldb.com/?id.218452Permissions Required, Third Party Advisory
Technical write-ups (may include proof of concept)
- gist.githubusercontent.com/gmcabrita/e5dc0332473fc2e3a7a407434c8d21c7/raw/00b12035e5e1b685469f143b94301a50306…Exploit, Third Party Advisory
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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