CVE-2023-52523
Description
This Linux kernel vulnerability in the sockmap subsystem occurs when a BPF sk_msg program attempts to redirect a message's egress from a TCP socket to a non-TCP socket, such as UDP. Because the underlying kernel call-chain hardcoded the assumption that the target would always be a TCP socket, this invalid downcast leads to a NULL pointer dereference and a subsequent kernel crash. The issue is resolved in patched kernel versions by explicitly rejecting non-TCP redirect targets for sk_msg programs, safely returning an EACCES error rather than crashing the system.
Statement
This vulnerability is rated as Low severity because exploiting it requires privileged access, specifically capabilities such as CAP_BPF or CAP_NET_ADMIN, to load and configure custom eBPF programs on the host. An attacker with sufficient privileges could trigger a system crash by redirecting traffic to an incompatible socket type via sockmap programs, resulting in a local denial of service. The flaw cannot be leveraged remotely and does not facilitate privilege escalation or data exposure.
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 | 5.5 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: 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:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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