CVE-2026-46306 flow_dissector: do not dissect PPPoE PFC frames

What is CVE-2026-46306?

CVE-2026-46306 is a high-severity denial of service vulnerability in Linux kernel, published on 8 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

flow_dissector: do not dissect PPPoE PFC frames

RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the flow dissector driver has assumed an uncompressed frame until the blamed commit.

During the review process of that commit [1], support for PFC is suggested. However, having a compressed (1-byte) protocol field means the subsequent PPP payload is shifted by one byte, causing 4-byte misalignment for the network header and an unaligned access exception on some architectures.

The exception can be reproduced by sending a PPPoE PFC frame to an ethernet interface of a MIPS board, with RPS enabled, even if no PPPoE session is active on that interface:

$ 0 : 00000000 80c40000 00000000 85144817 $ 4 : 00000008 00000100 80a75758 81dc9bb8 $ 8 : 00000010 8087ae2c 0000003d 00000000 $12 : 000000e0 00000039 00000000 00000000 $16 : 85043240 80a75758 81dc9bb8 00006488 $20 : 0000002f 00000007 85144810 80a70000 $24 : 81d1bda0 00000000 $28 : 81dc8000 81dc9aa8 00000000 805ead08 Hi : 00009d51 Lo : 2163358a epc : 805e91f0 __skb_flow_dissect+0x1b0/0x1b50 ra : 805ead08 __skb_get_hash_net+0x74/0x12c Status: 11000403 KERNEL EXL IE Cause : 40800010 (ExcCode 04) BadVA : 85144817 PrId : 0001992f (MIPS 1004Kc) Call Trace: [<805e91f0>] __skb_flow_dissect+0x1b0/0x1b50 [<805ead08>] __skb_get_hash_net+0x74/0x12c [<805ef330>] get_rps_cpu+0x1b8/0x3fc [<805fca70>] netif_receive_skb_list_internal+0x324/0x364 [<805fd120>] napi_complete_done+0x68/0x2a4 [<8058de5c>] mtk_napi_rx+0x228/0xfec [<805fd398>] __napi_poll+0x3c/0x1c4 [<805fd754>] napi_threaded_poll_loop+0x234/0x29c [<805fd848>] napi_threaded_poll+0x8c/0xb0 [<80053544>] kthread+0x104/0x12c [<80002bd8>] ret_from_kernel_thread+0x14/0x1c

Code: 02d51821 1060045b 00000000 <8c640000> 3084000f 2c820005 144001a2 00042080 8e220000

To reduce the attack surface and maintain performance, do not process PPPoE PFC frames.

[1] https://lore.kernel.org/r/[email protected]

Weakness: CWE-198

Which versions are affected by CVE-2026-46306?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-46306?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-46306 being exploited?

There is no known exploitation of CVE-2026-46306 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-89651, BELL-CVE-2026-46306, DEBIAN-CVE-2026-46306, GHSA-vm8v-fr63-mfh4, ROOT-OS-DEBIAN-12-CVE-2026-46306, ROOT-OS-UBUNTU-2404-CVE-2026-46306 and 1 more.