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CVE-2023-53338

9.8 · CRITICAL

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_…

Published Sep 17, 2025CWE-416EPSS 0.55%

Overview

CVE-2023-53338 is a critical-severity vulnerability. It was published on September 17, 2025 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/065d5f17096ec9161180e2c890afdff4dc6125f2Refgit.kernel.org/stable/c/29b22badb7a84b783e3a4fffca16f7768fb31205Refgit.kernel.org/stable/c/65583f9e070db7bece20710cfa2e3daeb0b831d9Refgit.kernel.org/stable/c/67f8f2bae8e7ac72e09def2b667e44704c4d1ee1Refgit.kernel.org/stable/c/a97f221651fcdc891166e9bc270e3d9bfa5a0080Refgit.kernel.org/stable/c/d68c17402442f5f494a2c3ebde5cb82f6aa9160aRefgit.kernel.org/stable/c/e3f647e4b642f9f6d32795a16f92c116c138d2af

How CyberStrike helps

Frequently asked questions

What is CVE-2023-53338?

CVE-2023-53338 is a critical-severity vulnerability. It was published on September 17, 2025 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2023-53338?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2023-53338?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2023-53338?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2023-53338 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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