Junos OS Evolved: Improper Neutralization of Special Elements used in an OS Command
CVE-2024-39524 is a high-severity improper neutralization of special elements used in an OS command vulnerability in Junos OS Evolved from Juniper Networks, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 20.4R3-S7-EVO, 21.2R3-S8-EVO, 21.4R3-S7-EVO as the first without the flaw, so updating Junos OS Evolved to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.25% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Junos OS Evolved to 20.4R3-S7-EVO or 21.2R3-S8-EVO or 21.4R3-S7-EVO or 22.2R3-EVO, whichever matches your release line, or a later version.
- Read the advisory on supportportal.juniper.net for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Juniper Networks | Junos OS Evolved | before 20.4R3-S7-EVO; 21.2-EVO up to, but not including, 21.2R3-S8-EVO; 21.4-EVO up to, but not including, 21.4R3-S7-EVO; 22.2-EVO up to, but not including, 22.2R3-EVO; 22.3-EVO up to, but not including, 22.3R2-EVO; 22.4-EVO up to, but not including, 22.4R2-EVO; before 20.4r3-s7; 21.2 up to, but not including, 21.2r3-8s; and 4 more ranges | 20.4R3-S7-EVO, 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.2R3-EVO, 22.3R2-EVO, 22.4R2-EVO |
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
- LocalThe attacker needs local access or must trick a user into running something.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.5 | High | CNA (juniper.net) |
| CVSS 3.1 | 7.8 | High | CNA (juniper.net) |
Official description
An Improper Neutralization of Special Elements vulnerability in Juniper Networks Junos OS Evolved commands allows a local, authenticated attacker with low privileges to escalate their privileges to 'root' leading to a full compromise of the system. The Junos OS Evolved CLI doesn't properly handle command options in some cases, allowing users which execute specific CLI commands with a crafted set of parameters to escalate their privileges to root on shell level. This issue affects Junos OS Evolved: All versions before 20.4R3-S7-EVO, 21.2-EVO versions before 21.2R3-S8-EVO, 21.4-EVO versions before 21.4R3-S7-EVO, 22.2-EVO versions before 22.2R3-EVO, 22.3-EVO versions before 22.3R2-EVO, 22.4-EVO versions before 22.4R2-EVO.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in an OS Command
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Improper Neutralization of Special Elements used in an OS Command vulnerabilities (CWE-78)
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
Other vulnerabilities in Junos OS Evolved
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.7 High severity
- 8.7 High severity
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