Executive Summary

This vulnerability exists in the Linux kernel's TIPC (Transparent Inter-Process Communication) subsystem, specifically in the tipc_buf_append() function.

The issue arises because tipc_msg_validate() can reallocate the skb (socket buffer) it is validating, freeing the old skb. However, tipc_buf_append() was calling tipc_msg_validate() with a pointer to a local copy of the skb pointer.

If the skb was reallocated and validation failed afterward, the error handling code would free the original skb pointer again, which had already been freed, causing a double-free vulnerability.

The fix involved checking if the head pointer now points to a newly allocated skb and, if so, reassigning the headbuf pointer for proper freeing later, preventing the double-free.

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Impact Analysis

A double-free vulnerability in the Linux kernel can lead to serious security issues such as system crashes, memory corruption, or potentially arbitrary code execution.

Exploitation of this vulnerability could allow an attacker to destabilize the system or escalate privileges, depending on the context in which the vulnerability is triggered.

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Mitigation Strategies

To mitigate this vulnerability, you should update your Linux kernel to a version where the double-free issue in tipc_buf_append() has been fixed.

The fix involves proper handling of skb pointers in the tipc_msg_validate() and tipc_buf_append() functions to prevent double-free errors.

Applying the latest kernel patches or upgrading to a kernel version released after 2026-06-24 is recommended.

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