Cisco Small Business Smart and Managed Switches: Buffer Copy without Checking Size of Input
CVE-2023-20162 is a critical-severity buffer copy without checking size of input vulnerability in Cisco Small Business Smart and Managed Switches from Cisco, 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. There is no confirmed exploitation so far. EPSS estimates a 1.51% chance of exploitation within 30 days, higher than 75% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update 250_series_smart_switches_firmware to 2.5.9.16 or a later version.
- Update 350_series_managed_switches_firmware to 2.5.9.16 or a later version.
- Update 350x_series_stackable_managed_switches_firmware to 2.5.9.16 or a later version.
- Read the advisory on sec.cloudapps.cisco.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; 35 further products are omitted here. 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 | 8.6 | High | CNA (cisco.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
Multiple vulnerabilities in the web-based user interface of certain Cisco Small Business Series Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or execute arbitrary code with root privileges on an affected device. These vulnerabilities are due to improper validation of requests that are sent to the web interface. For more information about these vulnerabilities, see the Details section of this advisory.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Buffer Copy without Checking Size of Input
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
More Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Cisco Small Business Smart and Managed Switches
- 7.7 High severity
- 7.2 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Buffer Copy without Checking Size of Input vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
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