CVE-2025-68785
Description
A slab-out-of-bounds read vulnerability was found in the Linux kernel's Open vSwitch (OVS) module. The push_nsh() action does not validate the middle nested attribute (OVS_KEY_ATTR_NSH) between the outer action and inner key attributes. When the middle attribute has an incorrect size, the nla_data() unwrap causes invalid memory access during action execution, leading to a KASAN-detected out-of-bounds read.
Statement
This vulnerability affects systems using Open vSwitch with NSH (Network Service Header) encapsulation. Exploitation requires the ability to configure OVS flow rules, typically requiring root or CAP_NET_ADMIN privileges. The out-of-bounds read occurs during action execution after validation passes due to larger netlink buffer during validation.
Mitigation
To mitigate this issue, prevent the openvswitch module from being loaded if Open vSwitch functionality is not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 7.1 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Understanding the Weakness (CWE)
Other,Integrity,Availability
Technical Impact: Varies by Context; DoS: Resource Consumption (CPU); Modify Memory; Read Memory
When the quantity is not properly validated, then attackers can specify malicious quantities to cause excessive resource allocation, trigger unexpected failures, enable buffer overflows, etc.
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