CVE-2026-43011
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Double Free in Linux Kernel X.25 Protocol

Publication date: 2026-05-01

Last updated on: 2026-05-07

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/x25: Fix potential double free of skb When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at line 48 and returns 1 (error). This error propagates back through the call chain: x25_queue_rx_frame returns 1 | v x25_state3_machine receives the return value 1 and takes the else branch at line 278, setting queued=0 and returning 0 | v x25_process_rx_frame returns queued=0 | v x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb) again This would free the same skb twice. Looking at x25_backlog_rcv: net/x25/x25_in.c:x25_backlog_rcv() { ... queued = x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); }
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Meta Information
Published
2026-05-01
Last Modified
2026-05-07
Generated
2026-06-16
AI Q&A
2026-05-01
EPSS Evaluated
2026-06-15
NVD
EUVD
Affected Vendors & Products
Showing 18 associated CPEs
Vendor Product Version / Range
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel From 5.11 (inc) to 5.15.203 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.22 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.168 (exc)
linux linux_kernel From 6.19 (inc) to 6.19.12 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.81 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.134 (exc)
linux linux_kernel From 2.6.12.1 (inc) to 5.10.253 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-415 The product calls free() twice on the same memory address.
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Executive Summary

This vulnerability is a potential double free issue in the Linux kernel's X.25 networking code. Specifically, when the function alloc_skb fails in x25_queue_rx_frame, it frees a socket buffer (skb) and returns an error. However, this error causes the skb to be freed again later in the call chain by x25_backlog_rcv, resulting in the same skb being freed twice.

Double freeing memory can lead to undefined behavior, including memory corruption or crashes.

Impact Analysis

The double free vulnerability can cause instability in the Linux kernel, potentially leading to system crashes or memory corruption. This can affect the reliability and availability of systems running vulnerable versions of the Linux kernel, especially those using the X.25 networking protocol.

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