CVE-2023-53338

High

In the Linux kernel, the following vulnerability has been resolved: lwt: Fix return values of BPF xmit ops BPF encap ops can return different types of positive values, such like NET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function skb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return values would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in ip(6)_finish_output2. When this happens, skbs that have been freed would continue to the neighbor subsystem, causing use-after-free bug and kernel crashes. To fix the incorrect behavior, skb_do_redirect return values can be simply discarded, the same as tc-egress behavior. On the other hand, bpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU information. Thus convert its return values to avoid the conflict with LWTUNNEL_XMIT_CONTINUE.

Package Linux Kernel
Published 2025-09-17
Last modified 2026-01-14
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type

CWE-416

CVE-2023-53338 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 4.10 and later are affected. Fixed in 5.4.257, 5.10.195, 5.15.132, 6.1.53, 6.4.16, 6.5.3, 6.6 and their respective stable series.

Affected from
≥ 4.10
Fixed in
✓ 5.4.257 5.4.x ✓ 5.10.195 5.10.x ✓ 5.15.132 5.15.x ✓ 6.1.53 6.1.x ✓ 6.4.16 6.4.x ✓ 6.5.3 6.5.x ✓ 6.6

References

The following references provide additional information about CVE-2023-53338 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

7 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2023-53338?

    CVE-2023-53338 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 4.10 onward and has been patched in 5.4.257, 5.10.195, 5.15.132 and others. CVE-2023-53338 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2023-53338?

    CVE-2023-53338 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2023-53338?

    Yes — CVE-2023-53338 has been patched. Fixed versions include 5.4.257, 5.10.195, 5.15.132 and others. If you are running Linux kernel 4.10 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2023-53338 actively exploited?

    No — CVE-2023-53338 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Use After Free (CWE-416)?

    The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. View CWE-416 on MITRE CWE →

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