nautobot: Improper Control of Generation of Code
CVE-2023-25657 is a critical-severity improper control of generation of code vulnerability in nautobot, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected nautobot versions: < 1.5.7. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.53% chance of exploitation within 30 days, higher than 75% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of nautobot 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.
- 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
- 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:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (github.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
Nautobot is a Network Source of Truth and Network Automation Platform. All users of Nautobot versions earlier than 1.5.7 are impacted by a remote code execution vulnerability. Nautobot did not properly sandbox Jinja2 template rendering. In Nautobot 1.5.7 has enabled sandboxed environments for the Jinja2 template engine used internally for template rendering for the following objects: `extras.ComputedField`, `extras.CustomLink`, `extras.ExportTemplate`, `extras.Secret`, `extras.Webhook`. While no active exploits of this vulnerability are known this change has been made as a preventative measure to protect against any potential remote code execution attacks utilizing maliciously crafted template code. This change forces the Jinja2 template engine to use a `SandboxedEnvironment` on all new installations of Nautobot. This addresses any potential unsafe code execution everywhere the helper function `nautobot.utilities.utils.render_jinja2` is called. Additionally, the documentation that had previously suggesting the direct use of `jinja2.Template` has been revised to suggest `render_jinja2`. Users are advised to upgrade to Nautobot 1.5.7 or newer. For users that are unable to upgrade to the latest release of Nautobot, you may add the following setting to your `nautobot_config.py` to apply the sandbox environment enforcement: `TEMPLATES[1]["OPTIONS"]["environment"] = "jinja2.sandbox.SandboxedEnvironment"` After applying this change, you must restart all Nautobot services, including any Celery worker processes. **Note:** *Nautobot specifies two template engines by default, the first being “django” for the Django built-in template engine, and the second being “jinja” for the Jinja2 template engine. This recommended setting will update the second item in the list of template engines, which is the Jinja2 engine.* For users that are unable to immediately update their configuration such as if a Nautobot service restart is too disruptive to operations, access to provide custom Jinja2 template values may be mitigated using permissions to restrict “change” (write) actions to the affected object types listed in the first section. **Note:** *This solution is intended to be stopgap until you can successfully update your `nautobot_config.py` or upgrade your Nautobot instance to apply the sandboxed environment enforcement.*
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
Patches and release notes
Other references
Other vulnerabilities in nautobot
- 7.1 High severity
- 8.5 High severity
- 7.1 High severity
Recent Improper Control of Generation of Code vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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