smarty: Improper Control of Generation of Code
CVE-2022-29221 is a high-severity improper control of generation of code vulnerability in smarty from Smarty-php, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected smarty versions: < 3.1.45; >= 4.0.0, < 4.1.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 4.91% chance of exploitation within 30 days, which is in the top 7.75% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of smarty you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Smarty-php | smarty | < 3.1.45; >= 4.0.0, < 4.1.1 | Not stated |
| Debian | Debian Linux | 9.0; 10.0; 11.0 | Not stated |
| Fedora Project | Fedora | 36; 37 | 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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA (github.com) |
| CVSS 3.1 | 8.8 | High | NVD |
| CVSS 2.0 | 6.5 | Medium | NVD |
Official description
Smarty is a template engine for PHP, facilitating the separation of presentation (HTML/CSS) from application logic. Prior to versions 3.1.45 and 4.1.1, template authors could inject php code by choosing a malicious {block} name or {include} file name. Sites that cannot fully trust template authors should upgrade to versions 3.1.45 or 4.1.1 to receive a patch for this issue. There are currently no known workarounds.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Control of Generation of Code
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
How developers prevent this class of flaw
- Refactor your program so that you do not have to dynamically generate code.
- Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
More Improper Control of Generation of Code vulnerabilities (CWE-94)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/smarty-php/smarty/security/advisories/GHSA-634x-pc3q-cf4cThird Party Advisory
Patches and release notes
- github.com/smarty-php/smarty/commit/64ad6442ca1da31cefdab5c9874262b702cccdddThird Party Advisory
- github.com/smarty-php/smarty/releases/tag/v3.1.45Release Notes, Third Party Advisory
- github.com/smarty-php/smarty/releases/tag/v4.1.1Release Notes, Third Party Advisory
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2022/05/msg00044.htmlMailing List, Third Party Advisory
- security.gentoo.org/glsa/202209-09Third Party Advisory
- debian.org/security/2022/dsa-5151Third Party Advisory
Other references
Other vulnerabilities in smarty
- 8.1 High severity
- 7.3 High severity
Recent Improper Control of Generation of Code vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.2 High severity
- 9.9 Critical severity
- 7.8 High severity
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