Cisco Unified Computing System (Standalone): Improper Neutralization of Parameter/Argument Delimiters
CVE-2026-20200 is a high-severity improper neutralization of parameter/argument delimiters vulnerability in Cisco Unified Computing System (Standalone) from Cisco, 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 Cisco Unified Computing System (Standalone) versions: 4.3(1.230097); 4.3(1.230124); 4.3(1.230138), and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.73% chance of exploitation within 30 days, higher than 55% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Cisco Unified Computing System (Standalone) you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Unified Computing System (Standalone) | 4.3(1.230097); 4.3(1.230124); 4.3(1.230138); 4.3(2.230207); 4.3(2.230270); 4.3(2.240002); 4.3(3.240022); 4.3(3.240043); and 30 more ranges | Not stated |
| Cisco | Unified Computing System | 4.3\(1.230097\); 4.3\(1.230124\); 4.3\(1.230138\); 4.3\(2.230207\); 4.3\(2.230270\); 4.3\(2.240002\); 4.3\(3.240022\); 4.3\(3.240043\); and 30 more ranges | 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 CNA (cisco.com).
Official description
A vulnerability in the web-based management interface of Cisco IMC could allow an authenticated, remote attacker with low privileges to execute arbitrary commands on the underlying operating system of an affected system and elevate privileges to root. This vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by entering crafted inputs to the web-based management interface of the affected software. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system as the root user.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Parameter/Argument Delimiters
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as parameter or argument delimiters when they are sent to a downstream component.
How developers prevent this class of flaw
- Developers should anticipate that parameter/argument delimiters will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
- While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
More Improper Neutralization of Parameter/Argument Delimiters vulnerabilities (CWE-141)
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
Other vulnerabilities in Cisco Unified Computing System (Standalone)
- 7.1 High severity
- 8.8 High severity
- 9.8 Critical severity
- 7.1 High severity
- 8.8 High severity
- 8.7 High severity
Recent Improper Neutralization of Parameter/Argument Delimiters vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
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