CVE-2023-53559
Description
A use-after-free flaw was found in the Linux kernel's ip_vti (IPsec Virtual Tunnel Interface) implementation when transmitting IPv6 packets with the SFB qdisc attached. A local user with CAP_NET_ADMIN capability can trigger this issue by configuring an ip_vti interface with an SFB qdisc and sending IPv6 traffic, causing the socket buffer control block to be modified during packet enqueuing and subsequently accessed after potential freeing during session decoding. This results in slab use-after-free, leading to kernel panic or potential memory corruption.
Statement
The ip_vti driver uses the socket buffer's control block (cb field) for internal state tracking. When the SFB (Stochastic Fair Blue) qdisc is attached to an ip_vti device, the qdisc modifies this cb field during packet enqueuing. Later, when decode_session6 is called on the transmit path, it attempts to access IP6CB(skb)->nhoff, which was designed only for the receive path and is not initialized during transmission. The modified cb field contents from the qdisc can cause the decoder to access invalid memory regions, potentially accessing already-freed slab objects.
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 | 6.7 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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