Cisco Small Business IP Phones: Missing Authentication for Critical Functionality
CVE-2023-20126 is a critical-severity missing authentication for critical functionality vulnerability in Cisco Small Business IP Phones 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 36.7% chance of exploitation within 30 days, which is in the top 1.48% of all scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Cisco Small Business IP Phones 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.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Small Business IP Phones | Not specified in the record | Not stated |
| Cisco | Spa112 Firmware | 1.4.1 | 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
- 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 | 9.8 | Critical | CNA (cisco.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
A vulnerability in the web-based management interface of Cisco SPA112 2-Port Phone Adapters could allow an unauthenticated, remote attacker to execute arbitrary code on an affected device. This vulnerability is due to a missing authentication process within the firmware upgrade function. An attacker could exploit this vulnerability by upgrading an affected device to a crafted version of firmware. A successful exploit could allow the attacker to execute arbitrary code on the affected device with full privileges. Cisco has not released firmware updates to address this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Authentication for Critical Functionality
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How developers prevent this class of flaw
- 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.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
- When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.
More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Cisco Small Business IP Phones
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
Recent Missing Authentication for Critical Functionality vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
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