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This vulnerability resides in the Linux kernel’s batman-adv (Better Approach to Mobile Ad-hoc Networking) module, which manages wireless mesh network routing. The flaw is an integer overflow in the `batadv_iv_ogm_send_to_if()` function, specifically with the `buff_pos` variable. `buff_pos` is declared as a signed 16-bit integer (s16), which has a maximum value of 32,767 (0x7FFF). During packet aggregation processing, the function `batadv_iv_ogm_aggr_packet()` performs a size check. This check uses a standard `int` (32-bit signed integer) for its calculations. An attacker can force `buff_pos` to be incremented repeatedly until it exceeds 32,767. When this limit is hit, the `s16` variable overflows and wraps around to a negative value (e.g., 32,768 becomes -32,768) due to two’s complement arithmetic. Since the bounds check was performed using an int, it does not anticipate this overflow. Consequently, the negative value is passed to a read function, causing it to access memory outside the bounds of the intended buffer. This out-of-bounds read can lead to a kernel panic (Denial of Service) or leak sensitive kernel memory (Information Disclosure), which could be used to bypass kernel security mechanisms like KASLR.
DailyCVE Form:
Platform: Linux Kernel
Version: 2.6.38–7.1-rc3
Vulnerability: Integer overflow
Severity: Critical (CVSS:8.8)
date: 2026-05-28
Prediction: 2026-06-28
What Undercode Say:
Check Kernel Version:
uname -r
Check batman-adv Module:
lsmod | grep batman_adv
Apply Patch (Git):
git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git cd linux git cherry-pick f61499359fa5 make && make modules_install
Apply Patch (Command):
sudo dnf update kernel
Check Patch Commit:
git show f61499359fa529f0d45a53bf7c573a49eb6322e6
Exploit:
This vulnerability requires local system access or proximity to the mesh network. An attacker can repeatedly send specially crafted OGM (Originator Message) packets. By crafting packets that cause `buff_pos` to overflow exactly at the boundary, the negative index can be forced. The specific address read during the out-of-bounds condition depends on the kernel memory layout, but successful exploitation could expose function pointers or sensitive stack data.
Protection:
Update the Linux kernel to version 6.6.140, 6.12.90, 6.18.32, 7.0.9, or 7.1-rc4 or later. If patching is not immediately possible, disable the batman-adv module (sudo modprobe -r batman_adv) if mesh functionality is not required, as this eliminates the attack surface entirely.
Impact:
Successful exploitation leads to an out-of-bounds read (CWE-125), potentially exposing sensitive kernel memory (Confidentiality) and causing a system crash (Availability). This could allow an unauthenticated attacker to bypass kernel security protections, potentially leading to further privilege escalation.
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Sources:
Reported By: nvd.nist.gov
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