CVE-2026-98952 pfcp: make sure the SEID is linear before reading it
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-98952?
CVE-2026-98952 is a high-severity vulnerability in Linux, published on 23 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-98952?
How do I fix CVE-2026-98952?
Upgrade to a fixed version.
Is CVE-2026-98952 being exploited?
There is no known exploitation of CVE-2026-98952 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98952, DEBIAN-CVE-2026-98952, GHSA-cvm8-2x36-72mp, UBUNTU-CVE-2026-98952.