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PatchSiren cyber security CVE debrief

CVE-2026-46306 Linux CVE debrief

A vulnerability has been resolved in the Linux kernel related to the flow dissector and PPPoE PFC frames. RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. The flow dissector driver has assumed an uncompressed frame until a specific commit. 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.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-08
Original CVE updated
2026-06-14
Advisory published
2026-06-08
Advisory updated
2026-06-14

Who should care

Users of the Linux kernel should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The vulnerability has a CVSS score of 7.5 and is classified as HIGH severity. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Defensive priority

HIGH

Recommended defensive actions

  • Update the Linux kernel to the latest version
  • Disable PFC for PPPoE sessions

Evidence notes

The vulnerability has been resolved in the Linux kernel. The fix is available in the stable kernel versions.

Official resources

public