PPPoE Header Vulnerability in Linux Kernel
CVE-2026-68121
Key Information:
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What is CVE-2026-68121?
A vulnerability in the Linux kernel's PPPoE implementation allows for header pointer mismanagement during device header callbacks. When a send action is blocked, it can lead to an invalidated pointer within the socket buffer (skb) head. This issue arises specifically when transitioning from a non-Ethernet port to an empty team device, where the delegated GRE header callback expands the skb head. Consequently, stale pointers may result in writing through freed memory, creating a potential security risk. To mitigate this, a solution involves reloading the PPPoE header after the creation of the device header, ensuring the proper offset is maintained.
Affected Version(s)
Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7a56e7c9b08e08fd55a1bcada24cf4fe3782b722
Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6eed5ae7887a93160803d2b81ff88e75eefd4a4c
Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Exploit Proof of Concept (PoC)
PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.