CVE-2026-68296
Description
A flaw was found in the Linux kernel's Generic Routing Encapsulation (GRE) tunnel implementation. An issue with how lockless transmission was handled for GRE tunnels with Sequence Number (SEQ) or Checksum (CSUM) features could lead to a deadlock. This deadlock occurs when the GRE transmit function re-enters the network stack, potentially causing the system to become unresponsive, resulting in a Denial of Service (DoS).
Statement
This issue affects GRE tunnels with SEQ/CSUM features. Removal of NETIF_F_LLTX handling broke lockless transmit for sequenced GRE tunnels. Systems using plain GRE without SEQ/CSUM are less affected.
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 | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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