Cisco Enterprise NFV Infrastructure Software: Improper Restriction of XML External Entity Reference
CVE-2022-20780 is a high-severity improper restriction of XML external entity reference vulnerability in Cisco Enterprise NFV Infrastructure Software from Cisco, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. There is no confirmed exploitation so far. EPSS estimates a 11.2% chance of exploitation within 30 days, which is in the top 3.97% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update Enterprise Nfv Infrastructure Software to 4.7.1 or a later version.
- 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.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Enterprise NFV Infrastructure Software | Not specified in the record | Not stated |
| Cisco | Enterprise Nfv Infrastructure Software | before 4.7.1 | 4.7.1 |
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
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.9 | Critical | CNA (cisco.com) |
| CVSS 3.1 | 7.4 | High | NVD |
| CVSS 2.0 | 4.3 | Medium | NVD |
Official description
Multiple vulnerabilities in Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an attacker to escape from the guest virtual machine (VM) to the host machine, inject commands that execute at the root level, or leak system data from the host to the VM. 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: Improper Restriction of XML External Entity Reference
The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.
How developers prevent this class of flaw
- Many XML parsers and validators can be configured to disable external entity expansion.
More Improper Restriction of XML External Entity Reference vulnerabilities (CWE-611)
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 Cisco Enterprise NFV Infrastructure Software
- 7.1 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 9.9 Critical severity
Recent Improper Restriction of XML External Entity Reference vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.8 High severity
- 7.5 High severity
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