In the Linux kernel, the following vulnerability has been resolved:
icmp6: Fix null-ptr-deref of ip6_null_entry->rt6i_idev in icmp6_dev().
With some IPv6 Ext Hdr (RPL, SRv6, etc.), we can send a packet that has the link-local address as src and dst IP and will be forwarded to an external IP in the IPv6 Ext Hdr.
For example, the script below generates a packet whose src IP is the link-local address and dst is updated to 11::.
# for f in $(find /proc/sys/net/ -name *seg6_enabled*); do echo 1 > $f; done # python3 >>> from socket import * >>> from scapy.all import * >>> >>> SRC_ADDR = DST_ADDR = "fe80::5054:ff:fe12:3456" >>> >>> pkt = IPv6(src=SRC_ADDR, dst=DST_ADDR) >>> pkt /= IPv6ExtHdrSegmentRouting(type=4, addresses=["11::", "22::"], segleft=1) >>> >>> sk = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW) >>> sk.sendto(bytes(pkt), (DST_ADDR, 0))
For such a packet, we call ip6_route_input() to look up a route for the next destination in these three functions depending on the header type.
* ipv6_rthdr_rcv() * ipv6_rpl_srh_rcv() * ipv6_srh_rcv()
If no route is found, ip6_null_entry is set to skb, and the following dst_input(skb) calls ip6_pkt_drop().
Finally, in icmp6_dev(), we dereference skb_rt6_info(skb)->rt6i_idev->dev as the input device is the loopback interface. Then, we have to check if skb_rt6_info(skb)->rt6i_idev is NULL or not to avoid NULL pointer deref for ip6_null_entry.
BUG: kernel NULL pointer dereference, address: 0000000000000000 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 157 Comm: python3 Not tainted 6.4.0-11996-gb121d614371c #35 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:icmp6_send (net/ipv6/icmp.c:436 net/ipv6/icmp.c:503) Code: fe ff ff 48 c7 40 30 c0 86 5d 83 e8 c6 44 1c 00 e9 c8 fc ff ff 49 8b 46 58 48 83 e0 fe 0f 84 4a fb ff ff 48 8b 80 d0 00 00 00 <48> 8b 00 44 8b 88 e0 00 00 00 e9 34 fb ff ff 4d 85 ed 0f 85 69 01 RSP: 0018:ffffc90000003c70 EFLAGS: 00000286 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 00000000000000e0 RDX: 0000000000000021 RSI: 0000000000000000 RDI: ffff888006d72a18 RBP: ffffc90000003d80 R08: 0000000000000000 R09: 0000000000000001 R10: ffffc90000003d98 R11: 0000000000000040 R12: ffff888006d72a10 R13: 0000000000000000 R14: ffff8880057fb800 R15: ffffffff835d86c0 FS: 00007f9dc72ee740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000057b2000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <IRQ> ip6_pkt_drop (net/ipv6/route.c:4513) ipv6_rthdr_rcv (net/ipv6/exthdrs.c:640 net/ipv6/exthdrs.c:686) ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:437 (discriminator 5)) ip6_input_finish (./include/linux/rcupdate.h:781 net/ipv6/ip6_input.c:483) __netif_receive_skb_one_core (net/core/dev.c:5455) process_backlog (./include/linux/rcupdate.h:781 net/core/dev.c:5895) __napi_poll (net/core/dev.c:6460) net_rx_action (net/core/dev.c:6529 net/core/dev.c:6660) __do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:554) do_softirq (kernel/softirq.c:454 kernel/softirq.c:441) </IRQ> <TASK> __local_bh_enable_ip (kernel/softirq.c:381) __dev_queue_xmit (net/core/dev.c:4231) ip6_finish_output2 (./include/net/neighbour.h:544 net/ipv6/ip6_output.c:135) rawv6_sendmsg (./include/net/dst.h:458 ./include/linux/netfilter.h:303 net/ipv6/raw.c:656 net/ipv6/raw.c:914) sock_sendmsg (net/socket.c:725 net/socket.c:748) __sys_sendto (net/socket.c:2134) __x64_sys_sendto (net/socket.c:2146 net/socket.c:2142 net/socket.c:2142) do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) RIP: 0033:0x7f9dc751baea Code: d8 64 89 02 48 c7 c0 ff f ---truncated---
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-livepatch-5.15.122-77.145Upgrade kernel-livepatch-5.10.192-182.736Upgrade bpftoolUpgrade kernel-debuginfoUpgrade kernelUpgrade kernel-livepatch-4.14.355-280.698Upgrade kernel-develUpgrade bpftool-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-debuginfoUpgrade python-perfUpgrade kernel-toolsUpgrade kernel-tools-develUpgrade perfUpgrade kernel-headersUpgrade python-perf-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade perf-debuginfo | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-tools-debuginfoUpgrade kernel-headersUpgrade perf-debuginfoUpgrade kernel-libbpfUpgrade kernel-develUpgrade perfUpgrade kernel-livepatch-6.1.41-63.109Upgrade bpftool-debuginfoUpgrade kernel-debuginfoUpgrade kernel-libbpf-staticUpgrade kernel-debuginfo-common-aarch64Upgrade kernelUpgrade python3-perfUpgrade python3-perf-debuginfoUpgrade kernel-tools-develUpgrade bpftoolUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-toolsUpgrade kernel-libbpf-devel | Sep 30, 2025 | Sep 17, 2025 |
| Debian | — | Upgrade linux | Sep 19, 2025 | Sep 19, 2025 |
| Huawei Euleros 2_0_sp10 | — | Upgrade python3-perfUpgrade kernel-tools-libsUpgrade kernelUpgrade kernel-abi-stablelistsUpgrade kernel-tools | Jan 15, 2026 | Jan 13, 2026 |
| Huawei Euleros 2_0_sp11 | — | Upgrade kernel-tools-libsUpgrade kernelUpgrade bpftoolUpgrade python3-perfUpgrade kernel-toolsUpgrade kernel-abi-stablelists | Mar 17, 2026 | Mar 17, 2026 |
| Huawei Euleros 2_0_sp12 | — | Upgrade bpftoolUpgrade kernel-abi-stablelistsUpgrade kernel-tools-libsUpgrade kernelUpgrade python3-perfUpgrade kernel-tools | Mar 17, 2026 | Mar 17, 2026 |
| Huawei Euleros 2_0_sp13 | — | Upgrade python3-perfUpgrade kernel-abi-stablelistsUpgrade kernelUpgrade bpftoolUpgrade kernel-toolsUpgrade kernel-tools-libs | Feb 3, 2026 | Jan 30, 2026 |
| Redhat_linux | — | Upgrade kernel-rtUpgrade kernelNo solution exists | Nov 14, 2025 | Sep 17, 2025 |
| Ubuntu | — | Upgrade linux-aws-fipsUpgrade linux-azure-fipsUpgrade linux-ibmUpgrade linux-raspi-5.4Upgrade linux-iotUpgrade linux-hwe-5.4Upgrade linux-azure-5.4Upgrade linux-gcp-fipsUpgrade linux-nvidia-tegra-igxUpgrade linux-gcp-5.15Upgrade linux-intel-iot-realtimeUpgrade linux-gcp-5.4Upgrade linux-awsUpgrade linux-intel-iotg-5.15Upgrade linux-oracleUpgrade linux-hwe-5.15Upgrade linux-gkeopUpgrade linux-gcpUpgrade linux-azure-5.15Upgrade linux-kvmUpgrade linux-bluefieldUpgrade linux-azureUpgrade linux-ibm-5.15Upgrade linux-lowlatency-hwe-5.15Upgrade linux-oracle-5.4Upgrade linux-gkeUpgrade linux-realtimeUpgrade linux-fipsUpgrade linux-riscv-5.15Upgrade linux-raspiUpgrade linux-lowlatencyUpgrade linux-xilinx-zynqmpUpgrade linuxUpgrade linux-nvidia-tegraUpgrade linux-oracle-5.15Upgrade linux-nvidia-tegra-5.15Upgrade linux-aws-5.15Upgrade linux-aws-5.4Upgrade linux-nvidiaUpgrade linux-intel-iotgUpgrade linux-ibm-5.4 | Sep 26, 2025 | Sep 17, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 15, 2025 | Sep 17, 2025 |
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