Executive brief
A vulnerability in the Linux kernel's networking component could allow an attacker to cause system instability or crashes. The issue affects PPPoE, a protocol commonly used by Internet Service Providers to connect users to the internet. By sending specially crafted network traffic, an attacker could trigger errors on certain hardware architectures, potentially leading to a denial of service.
Technical details
A vulnerability exists in the Linux kernel's PPPoE implementation where the generic PPP layer (ppp_input) incorrectly accepts Protocol Field Compression (PFC) frames despite PPPoE specifications recommending against them. When a compressed 1-byte protocol field is received instead of the expected 2-byte field, the subsequent PPP payload is shifted, causing network headers to become 4-byte misaligned. On certain hardware architectures, this misalignment triggers unaligned access exceptions, potentially leading to a kernel panic or denial of service. The fix introduces a check to drop PFC frames within the PPPoE receive path (pppoe_rcv).
Affected products
- Linux Linux 7fb1b8ca8fa1 to 0cab5d077dd1efd2bd1a47271acc35894f945b4f
Timeline
- 2026-04-15: patched: Initial patch authored
- 2026-06-24: disclosed: CVE published
References
- https://git.kernel.org/stable/c/0cab5d077dd1efd2bd1a47271acc35894f945b4f
- https://git.kernel.org/stable/c/2b5c3c040d020e3ab3b9a8887031202d96843b1e
- https://git.kernel.org/stable/c/49e41b60ccd1bdbe9e218420f716dd5f9a2f9c71
- https://git.kernel.org/stable/c/8a5e840babc5c0fbd10c73728a13192347771ec6
- https://git.kernel.org/stable/c/ba758fdf1399f310b30098b6faa3fd043de47dd2
- https://git.kernel.org/stable/c/cb3beef35ab5e0c1afca9fd7648c6ae499786377
- https://git.kernel.org/stable/c/cc1ff87bce1ccd38410ab10960f576dcd17db679