CVE-2026-98802CVE-2026-98802

In the Linux kernel, the following vulnerability has been resolved: seg6: ensure packet data is writable before modifying SRH and IPv6 DA advance_nextseg() modifies the SRH Segments Left field and the IPv6 destination address without ensuring the packet data is writable. seg6_next_csid_advance_arg() has the same problem when it advances the NEXT-C-SID argument in the destination address. The skb may be cloned, for example by an AF_PACKET socket receiving on the ingress device. advance_nextseg() and seg6_next_csid_advance_arg() then write into the packet data shared with the clone. A read from that socket can return the modified packet instead of the received one. The simplified path below shows this for advance_nextseg(): __netif_receive_skb_one_core __netif_receive_skb_core deliver_skb [orig: users=2, cloned=0] packet_rcv skb_clone clone queued to the AF_PACKET socket consume_skb(orig) [orig: users=1, cloned=1] ipv6_rcv