CVE-2023-53338
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-17

Last updated on: 2025-12-11

Assigner: kernel.org

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.
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Meta Information
Published
2025-09-17
Last Modified
2025-12-11
Generated
2026-05-07
AI Q&A
2025-09-17
EPSS Evaluated
2026-05-05
NVD
CVE-2023-53338
Affected Vendors & Products
Showing 6 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 4.10 (inc) to 5.4.257 (exc)
linux linux_kernel From 5.5 (inc) to 5.10.195 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.132 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.53 (exc)
linux linux_kernel From 6.2 (inc) to 6.4.16 (exc)
linux linux_kernel From 6.5 (inc) to 6.5.3 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel involves incorrect handling of return values from BPF (Berkeley Packet Filter) encapsulation operations during packet transmission. Specifically, certain positive return values from functions like skb_do_redirect and bpf_lwt_xmit_reroute are mistakenly treated as LWTUNNEL_XMIT_CONTINUE in the transmission hook. This causes packets (skbs) that have already been freed to be processed further, leading to a use-after-free bug and potential kernel crashes. The fix involves properly discarding or converting these return values to prevent this unsafe behavior.


How can this vulnerability impact me? :

This vulnerability can lead to kernel crashes due to use-after-free bugs when processing network packets. Such crashes can cause system instability, denial of service, or potentially allow attackers to exploit the kernel for further malicious actions, impacting system reliability and security.


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