CVE-2023-1668
Description
A flaw was found in openvswitch (OVS). When processing an IP packet with protocol 0, OVS will install the datapath flow without the action modifying the IP header. This issue results (for both kernel and userspace datapath) in installing a datapath flow matching all IP protocols (nw_proto is wildcarded) for this flow, but with an incorrect action, possibly causing incorrect handling of other IP packets with a != 0 IP protocol that matches this dp flow.
Statement
In OpenShift Container Platform (OCP) the openvswitch rpm package is consumed from the RHEL Fast Datapath repositories, hence OCP openvswitch components are marked as "Will not fix".
Mitigation
For any version of Open vSwitch, preventing packets with network
protocol number '0' from reaching Open vSwitch will prevent the issue.
This is difficult to achieve because Open vSwitch obtains packets before
the iptables or nftables host firewall, so iptables or nftables on the
Open vSwitch host cannot ordinarily block the vulnerability.
Another method would be to add a high priority flow to the flow table
explicitly matching on nw protocol '0' and handling that traffic
separately:
table=0 priority=32768,ip,ip_proto=0 actions=drop
This would need to be similarly done for IPv6 traffic as well.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.2 | 8.2 | 8.2 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Understanding the Weakness (CWE)
Other
Technical Impact: Other; Alter Execution Logic
Acknowledgements
This issue was discovered by David Marchand (Red Hat).
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