CVE-2026-98383

A flaw was found in the Linux kernel's BPF (Berkeley Packet Filter) subsystem. A local attacker with privileges to load BPF programs could exploit this vulnerability to cause a Denial of Service (DoS) or potentially corrupt system memory. The issue occurs when an IPv6 segment routing program modifies routing headers and subsequently triggers packet buffer reallocation, leaving an internal pointer referencing invalid memory. Subsequent validation routines write through this dangling pointer, resulting in memory corruption and a system crash.

An LWT_SEG6LOCAL BPF program can invalidate its cached SRH with bpf_lwt_seg6_adjust_srh() and then call bpf_skb_pull_data(), which may reallocate skb head and leave the per CPU SRH pointer dangling. Post program SRH validation can then write through the stale pointer, creating a write after free style memory corruption primitive in the host kernel. For the CVSS the PR:L value is used for the paranoid score because a reduced capability container root or service with delegated BPF and network administration capabilities may be able to load and attach the required program without full host root privileges. This is not directly network reachable because remote packets cannot install the unsafe BPF program, although packets can execute it after local configuration. Impact is at least a local denial of service and may include privilege escalation or host kernel compromise if the stale write can be shaped reliably.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.