pfcp: make sure the SEID is linear before reading it

Summary

In the Linux kernel, the following vulnerability has been resolved: pfcp: make sure the SEID is linear before reading it pfcp_encap_recv() only makes sure that the UDP header and the 4 byte PFCP header are in the linear area. When the S flag is set, pfcp_session_recv() then reads the 8 byte SEID that follows, which is not covered by the pskb_may_pull() check. A short PFCP packet with the S flag set, or one whose session header lies in a fragment, therefore makes pfcp_session_recv() read beyond the end of the packet data, and whatever it finds there is stored in the tunnel metadata that flower later classifies on. Pull up to the end of the SEID before reading it, and drop packets that are too short to contain it. Reload the header pointer afterwards since pskb_may_pull() may reallocate the skb head. Use offsetofend() rather than sizeof(struct pfcphdr_session): the structure is not packed, so its size is 16 bytes because of the alignment of the __be64 member, while the header on the wire is only 12 bytes, and valid session messages would be dropped.

Timeline

1. Oct 23, 2026, 12:19 PM UTCCVE published
2. Oct 23, 2026, 12:20 PM UTCFirst seen by cve.now
3. Oct 24, 2026, 2:09 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 6dd514f48110ebb4bf36875b9e7e02d07b589caa · fixed in 3192a5e398c64d48aad64a09e29643e327369bc4; From 6dd514f48110ebb4bf36875b9e7e02d07b589caa · fixed in b18a6496495495e2dc27e525aa3315a0c59b9513; From 6dd514f48110ebb4bf36875b9e7e02d07b589caa · fixed in 2fb6d05f706d79bbdc88835be2f4f45ab56dd819; From 6dd514f48110ebb4bf36875b9e7e02d07b589caa · fixed in 23609bce9e1de525d1d0e73fc68c6e7971d0b49e

• Linux Linux

  6.10

• KernelLinux

  From 6.10.0 · fixed in 6.12.113; From 6.13.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.11

References 4