External risk intelligence

Linux Kernel skbuff Use-After-Free Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2022-49093

This vulnerability is located deep within the Linux kernel's memory management and networking stack, specifically involving how skbuff page fragments are coalesced and recycled. It is an internal kernel-level implementation detail rather than an application-level interface. It does not represent a directly reachable service that can be exploited over the public internet.

Use After Free

Linux Kernel

5.15 to before 5.15.345.16 to before 5.16.205.17 to before 5.17.35.18

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the Linux kernel has been resolved, impacting its memory management and networking components. This issue, related to how data fragments are handled, has been addressed by the kernel developers. The primary concern is to confirm if systems utilize the affected kernel versions and to assess potential exposure.

Kernel flaw impacts data fragment handling.
Leadership should remember it relates to core operating system functions.
Confirm relevance and potential exposure of affected systems.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by triggering a specific sequence of network packet handling operations within the Linux kernel. This involves manipulating packet coalescing, where data from multiple packets is combined into a single buffer. When this process incorrectly manages page fragments during recycling, it can lead to a use-after-free condition.

No specific access required.
Triggered by packet coalescing operations.
Allows unauthorized code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the integrity of network data being processed by the Linux kernel when using specific page pool recycling mechanisms. Under supported conditions, a use-after-free flaw may lead to unpredictable service behavior.

Network packet data integrity.
Memory corruption via use-after-free.
Potential system instability or crashes.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability resides within the Linux kernel's network packet handling and memory recycling mechanisms. Infrastructure and platform teams are primarily responsible for managing the kernel. The initial step should be to identify all systems running the affected kernel versions, confirm their exposure, and then assess the business criticality of each system before planning remediation, which may involve coordinating with kernel maintainers or vendor support.

Identify affected kernel instances.
Verify reachability and business criticality.
Plan remediation based on identified risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

How does the Linux kernel manage network memory during packet operations?

The kernel uses structured buffers (skbuff) and page pools to track memory fragments efficiently. When processing incoming network traffic, the system coalesces multiple packets into a single buffer to optimize memory use. This involves precise reference counting of page fragments to ensure that the kernel can safely release or recycle the underlying memory once data processing is complete.

Which weakness class describes this kernel memory flaw?

This issue is classified as CWE-416, a Use-After-Free vulnerability. It arises when the system incorrectly tracks references to page fragments during the coalescing process. Specifically, the kernel fails to update the correct page pool fragment counter, causing memory references to be prematurely dropped while other components still expect the data to remain valid.

Does this vulnerability trigger through standard network packet processing?

Yes, the flaw is triggered during routine network activity, specifically when the kernel performs packet coalescing. It does not require unusual or complex inputs. However, it is limited to specific kernel implementations that use page pool fragment recycling; systems not utilizing these specific memory management features remain unaffected by this logic error.

How relevant is this vulnerability to external surface exposure?

According to the Halo Surface Signal, this vulnerability is very unlikely to be exploited over the public internet. Because the defect exists deep within the kernel's internal memory management for page fragments, it does not provide an easily reachable interface for external attackers to manipulate directly.

What is the recommended response for securing affected infrastructure?

Teams should first audit their environments to identify all systems running vulnerable Linux kernel versions. After assessing the criticality of these assets, prioritize patching by applying updates from official maintainers that correct the fragment reference counting logic. Remediation should focus on deploying these kernel updates to ensure stable memory handling.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.