The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - ipv6: seg6: clear IPv4 control block on IPIP decapsulation End.DX4 and End.DT4 decapsulate an IPv4 packet     through decap_and_validate() and send it directly to IPv4 routing. The inner packet therefore bypasses     ip_rcv_core(), which normally clears IPCB before IPv4 interprets skb->cb. The skb instead retains IP6CB     data from the outer packet. IP6CB and IPCB use the same skb->cb storage, so IP6CB(skb)->lastopt overlaps     IPCB(skb)->opt.optlen and srr, while IP6CB(skb)->nhoff overlaps rr and ts. The sender can make the stale     optlen byte nonzero with a valid outer extension-header chain. The reproducers put an eight-byte     Destination Options header immediately after the 40-byte IPv6 header and before the Segment Routing     Header. ipv6_destopt_rcv() records the sender-controlled Destination Options offset in both lastopt and     nhoff, setting them to 40. On the reproduced little-endian x86-64 kernel, IPv4 therefore sees optlen = 40     and rr = 40. Both tcp_v4_save_options() and __ip_options_echo() skip option copying when optlen is zero.
    Here optlen is 40, so the TCP SYN path allocates room for 40 bytes of option data and calls
    __ip_options_echo(). The stale rr value makes that function read inner packet byte 41 as the Record Route     option length. The reproducers set that sender-controlled byte to 255, so __ip_options_echo() copies 255     bytes into the 40-byte option-data area. Separate End.DX4 and End.DT4 reproducers on the unpatched     v7.2-rc5 kernel both produced: BUG: KASAN: slab-out-of-bounds in __ip_options_echo() Write of size 255 The     relevant End.DX4 call path is: __ip_options_echo tcp_v4_route_req tcp_conn_request tcp_v4_conn_request     tcp_rcv_state_process tcp_v4_do_rcv tcp_v4_rcv ip_protocol_deliver_rcu ip_local_deliver_finish     ip_local_deliver input_action_end_dx4_finish input_action_end_dx4 The relevant End.DT4 call path is:
    __ip_options_echo tcp_v4_route_req tcp_conn_request tcp_v4_conn_request tcp_rcv_state_process     tcp_v4_do_rcv tcp_v4_rcv ip_protocol_deliver_rcu ip_local_deliver_finish ip_local_deliver     input_action_end_dt4 tcp_v4_save_options() is inlined into the tcp_v4_route_req() path, so it does not     appear as a separate frame. When decap_and_validate() handles IPPROTO_IPIP, save the ingress interface     from IP6CB, clear IPCB, and restore the saved value. Doing this in the common decapsulation path covers     End.DX4, End.DT4, and End.DT46's IPv4 arm. Use IP6CB(skb)->iif rather than skb->skb_iif. These actions run     after l3mdev processing, which can replace skb_iif with the L3 master; IP6CB iif still records the     receiving interface set at IPv6 ingress. (CVE-2026-80840)

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Linux Distros Unpatched Vulnerability : CVE-2026-80840

medium Nessus Plugin ID 342967

Version 1.7