CVE-2026-80590
Description
A flaw was found in the Linux kernel's network fragment reassembly process. An unprivileged local user, or a guest in a virtualized environment, could craft specially formed IPv4 or IPv6 network fragments that incorrectly retain Generic Segmentation Offload (GSO) state after reassembly. This misinterpretation of network packet state can lead to a kernel panic, resulting in a Denial of Service (DoS) for the affected system.
Mitigation
To mitigate this issue, restrict the creation of unprivileged user namespaces. This can prevent unprivileged local users from exploiting the vulnerability via tap devices.
To disable unprivileged user namespaces, set the kernel.unprivileged_userns_clone sysctl to 0:
sysctl -w kernel.unprivileged_userns_clone=0
To make this change persistent across reboots, add the following line to a file in /etc/sysctl.d/, for example, /etc/sysctl.d/99-disable-userns.conf:
kernel.unprivileged_userns_clone = 0
After modifying the sysctl configuration, apply the changes:
sysctl --system
Disabling unprivileged user namespaces may impact applications that rely on this feature, such as container runtimes or sandboxing tools.
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 | 7.7 | N/A | 8.6 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability,Integrity,Confidentiality
Technical Impact: Read Memory; Modify Memory; Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart
When a memory buffer is accessed using the wrong type, it could read or write memory out of the bounds of the buffer, if the allocated buffer is smaller than the type that the code is attempting to access, leading to a crash and possibly code execution.
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