CVE-2026-80601 in Linux
Summary
by MITRE • 08/28/2026
In the Linux kernel, the following vulnerability has been resolved:
batman-adv: gw: acquire ethernet header only after skb realloc
The pskb_may_pull() called by batadv_get_vid() could reallocate the buffer behind the skb. Variables which were pointing to the old buffer need to be reassigned to avoid an use-after-free.
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Analysis
by VulDB Data Team • 08/28/2026
The Linux kernel vulnerability identified in the batman-adv (B.A.T.M.A.N. Advanced) module involves a critical memory management error within its gateway selection logic, specifically during the processing of Virtual LAN identifiers. The core issue stems from improper handling of socket buffer reallocation operations that can lead to use-after-free conditions. In network stack programming, particularly within kernel space where direct memory access is prevalent, maintaining pointer validity after potential buffer modifications is essential for system stability and security.
The technical flaw occurs in the batadv_get_vid function which invokes pskb_may_pull to ensure sufficient data is present in the socket buffer skb for subsequent processing operations. The pskb_may_pull function may trigger a reallocation of the underlying memory buffer if the current allocation does not contain enough contiguous bytes or meets certain fragmentation criteria. When this reallocation happens, the original memory address stored in local variables pointing into that buffer becomes stale and invalid. However, the code continues to reference these outdated pointers assuming they still point to valid data within the socket structure.
This dereferencing of freed or relocated memory constitutes a classic use-after-free vulnerability classified under CWE-416. By accessing memory through pointers that no longer correspond to the active buffer location, the kernel risks reading corrupted data or writing to unintended memory regions. In worst-case scenarios involving crafted network packets designed specifically to trigger this reallocation path, an attacker could potentially achieve arbitrary code execution with kernel privileges by controlling what gets written into the newly allocated space or exploiting race conditions during the transition between old and new buffer states.
The operational impact of this vulnerability extends beyond simple data corruption as it compromises the integrity of the batman-adv gateway selection mechanism which is crucial for mesh network routing efficiency. If an attacker successfully exploits this flaw, they could disrupt network connectivity by causing kernel panics or system crashes through memory corruption that destabilizes adjacent structures in kernel heap space. Furthermore successful exploitation might allow lateral movement within protected networks if the compromised node serves as a critical routing point for other devices relying on batman-adv mesh networking capabilities.
Mitigation strategies primarily involve applying vendor-provided patches that update the batman-adv module to properly reassign pointers after calling pskb_may_pull ensuring all references remain valid relative to potentially relocated buffers developers implementing similar network processing code should adopt defensive programming practices by always verifying pointer validity post-reallocation functions and considering alternative approaches like copying required data into separate stable buffers before performing operations that might trigger memory moves.
From a defense-in-depth perspective organizations deploying batman-adv mesh networks should monitor for unusual kernel log messages indicating memory errors or segmentation faults which may signal attempted exploitation attempts while keeping systems updated with latest security patches addressing this specific CWE-416 issue within the Linux kernel networking subsystems to maintain robust protection against such low-level memory corruption attacks.